. Aquarium and Pond UV Sterilizer, Clarifier Reviews; Problems

UV Sterilizer Reviews; Information Articles, Ideas, Comments, and Links to even more Resources about how UVC Sterilization works in Aquariums/ Ponds

aquarium and pond UV posts, information, articles, resources, blogs

Information Articles (Posts), Ideas, Comments, & Links to even more Information about how UV (UVC) Sterilization works in Aquariums/ Ponds.
For a COMPLETE up to date article about aquarium and pond uv sterilization, please visit this site:
UV Sterilization in Aquariums and Ponds; How it works

For all Articles, from basic to advanced, such as UVC, Watts, mW/cm2, please scroll down the Right Side Bar of this site for easy links

Green Pond Water, UV Clarifier


Revised 3/2/19

Green Pond UV Clarifier or Sterilizer Use

Green or Clear Pond

Green or Clear Pond?
The picture above albeit two different ponds demonstrates what is clearly the more desirable pond.

There are many causes and cures to this problem, however the use of a correctly applied UV Sterilizer/Clarifier is the most simple and popular, of which the correct application is the focus of this article.

This includes Placement, Flow, & Turnover among other factors

First though, let me briefly explain the causes:

Green water is caused by the accumulation of millions of single cell, microscopic spores of green algae suspended in the water. These single cell algae have the ability to turn your originally clear pond into what looks like pea green soup.

The main causative agent to green pond water is the sun.
Sunlight while in itself is necessary and healthy for life (such as Redox), excessive exposure can and will cause algae problems. The result is what is referred to as an "algae bloom" is when single cell green algae reproduces at a fast rate, as a result of sunlight and nutrients in the water.
Outside of shade by both or either plants or overhead trellises, not much can be done about sunlight (although seasons have a major impact on sunlight since the winter sun does not have nearly the impact of the summer sun, especially in higher latitudes).

Nutrients are the other primary causative agent, which in itself can have many causes from high fish bio load, poor filtration, accumulation of decaying organic matters, etc.

Good and regular maintenance can control decomposition of waste, while adequate filtration, especially a Veggie/Bog Plant Filter can help greatly by reducing nitrates in the water.

Reference this article for further information:
Pond Veggie/Bog Plant Filters

Other methods of Green Pond Water Control are listed here:

Pond UV Sterilizer, Clarifier for green water
Often many basic methods still fail to control these algae blooms and this is where a UV Sterilizer (as well as UV Clarifiers) comes in.
See this website for good to premium pond TRUE UV Sterilizers: Pond & Aquarium UV Sterilizers

The key is flow, correct wattage as per flow, dwell time, pond turnover, & placement

with flow rate, this should be under 50 gallons per hour per watt of UVC for most Compact UVsand as low as 40 gph per watt for many low end Basic UV Clarifiers that utilize poor dwell time and low output medium pressure UV Bulbs.
With higher dwell time "True" UV Sterilizers this rate can be as high as 60-70 gallons per watt of output UV energy (a "True" UV Sterilizer is one that maintains level one UV Sterilization or higher versus the many low end units often sold on eBay, Amazon, etc. that are only capable of basic clarification).
It is noteworthy that generally straight tube designs have a higher dwell time.

Premium Level One UV Sterilizer Resource:
AAP/TMC Pond UV-C Sterilizer, Clarfifier

Turnover is sometimes tricky with pond as although it does not need to be high for Green Water control (Once per 2-3 hours), the shape of the pond and more often, flow patterns may not allow for coverage of the entire pond.

What I mean is unlike most aquariums which tend to have relatively even circulation; many ponds may have one zone that has good circulation and another that does not.
The result is an area of the pond with poor circulation, along with sunlight and nutrients resulting in these green water producing algae spores.
Please also reference this UV Sterilization article section dealing with flow rate and turnover:
Pond Green Water Flow Rate Table

You can test this with dyes or even relatively harmless aquatic products such as Methylene Blue
For more Kordon Products such as Methylene Blue please see:
Kordon Methylene Blue from AAP

The solution, especially of you have a pond shape with more than one interconnected pond, is separate pumps/filters with separate UV Sterilizers.
As well, the use of Veggie/Bog filter as mentioned earlier (especially in areas of constriction) can lower nutrients so that the UV Sterilizer does not work as hard.
I would add that even with ponds in more formal rectangle or similar shape, separate flow patterns may still yield best results.

If one UV (with proper flow/dwell time) is not sufficient, adding another immediately in-line can improve results. However I will still state from my experience two separate UVs will often yield better results than two in-line.

An example would be the use of one 30 Watt AAP/TMC PRO UV Pond Clarifier (which is one of the best if not the best) for a pond up to 7000 gallons run with a flow rate of 2100 gph. This is clearly at the edge of this UVs operation envelope and although it make work well with optimum conditions (including a Veggie Filter), under other conditions such as high bio loads and considerable direct sunlight the addition of a second UV either in parallel on another pump (recommended) or inline on the same pump.

Resource: 30 Watt AAP/TMC PRO Pond UV Clarifiers

TMC 110 Watt Professional Large Pond UV Sterilizer & clarifier for green waterAnother idea for larger ponds in particular, is the use of large professional hard plumbed UV Sterilizer where by the water is split to different locations after passing through the UV Sterilizer to provide more even circulation.
Of course a large UV Sterilizer can also be used on multiple lines for exceptionally large pond or ponds that have high sun exposure with marginal bio filtration (although I still recommend a Veggie/Bog filter for any pond, no matter how large, as a UV Sterilizer should not be your only algae/green water control tool).

Easily the most exceptional high capacity professional UV Sterilizer for "hard plumbing" into one's pond is the TMC 110 Watt Professional Large Pond UV Sterilizer. Quite bluntly in my 35 years of professional pond design and maintenance, I have never found a more efficient UV sterilizer AT ANY PRICE (often I have spent much more for lesser results).
Resource: TMC 110 Watt Professional Large Pond/Aquarium UV Sterilizer/Clarifier

Aqua UV versus TMC UV Sterilizer
VIDEO: Aqua Pond UV vs TMC AAP Pond UV Clarifier Sterilizer

A comparison of the two top large pond/aquarium-system UV Sterilizers and why the AAP/TMC comes out as the best when price and dwell time is considered

This is important too, you first want to remove as many dissolved waste particulates from the water as possible as these can and do block UVC irradiation, making your UV Sterilizer less effective.

See/Reference: UV Transmittance; Other Factors Affecting UVC Sterilization Pre-Filtration & Turbidity

This is done by pre-filtering the water prior to entering into the UV Sterilizer, even if by just small sponge filter, gravel rock filter, etc.
Adding highly porous volcanic rock around a pump, even if it already has a sponge pre-filter can GREATLY help in pre-filtration of your pond water prior to entering the UV Sterilizer. This not only allows for a more effective UV Sterilizer, but also iads in keeping your pump from clogging with debris or the pre-filter sponge from clogging quickly

Product Resource: Volcanic Rock for Pond or Aquarium

Pond UV Circulation

Another essential of placement is to make sure that the pickup of the water to the UV is not close to the return, so as to provide as best of over all circulation as possible.

One can also install two (or more) smaller "loops of water" with multiple UV Sterilizers for better circulation with larger or irregular shaped ponds.

See also:
Pond Care Information; UV Sterilizer Use

Finally as per choosing a UV sterilizer, I will admit my bias, if it was/is not already apparent, and that is for the TMC Advantage professional line of UV Sterilizers.

I have been in the business of professionally maintaining ponds and aquariums since 1978, specializing in UV-C Sterilization.
I have tested and used most every brand and type of UV Sterilizer, I have even built my own from scratch. As well I have used and tested many brands of UV Bulbs for these units from cold cathode to superior Hot Cathode UV Bulbs, finding these albeit more difficult to light due to requirement of a peak voltage ballast, but vastly higher UVC output resulting in better sterilization and clarification (95% for the hot cathode versus 25% UVC output for the cold cathode).

See these web pages for recommended resources based on my professional UV Sterilizer design and use experience dating back to 1978: *Premium Hot Cathode UV Bulbs
*AAP/TMC Advantage professional line of Pond UV Sterilizers

My point is I have found the construction of the TMC Advantage UVs very solid and durable with flow/dwell time patterns second to none including often higher priced Aqua, Emperor, and Laguna UVs.
Just as importantly, when replacement parts are needed, TMC makes most all part easily available and reasonably priced; which I cannot say is the same for most other popular UVs.
When compared to the Tetra, another higher priced UV, the Advantage has a vastly superior flow design and dwell time (no compact UV such as the Tetra can compete with a straight tube for dwell time based on real world tests)

For more on Dwell time, please reference:
UV Dwell Time Test

Then there are all the submersible UV's such as the AquaTop that while I have used them, with some success; these ultra low cost UV's simply do not hold up long term in a harsh pond environment and eventually fail. As well these UV's often cannot clear green water unless conditions are otherwise optimum.

In summary when choosing a true level 1 capable UV Sterilizer over a low cost UV Clarifier, one might ask why bother spend the extra when all that is desired is clarification??

The answer is simple; a True level 1 capable UV can clear water at much higher flow rates, much more quickly sometimes in hours where as a UV Clarifier will often require days for the exact same pond!!
As well, the level one capable UV will improve Redox, which improves fish & pond health, and aid in disease prevention; something a UV Clarifier CANNOT perform.
Finally, many true UV Sterilizers are simply better built, which means you will likely get many years of service versus just one or two which is common to many of the lower quality UV clarifiers, including some of the more over rated models such as the Turbo Twist.
Reference: Turbo Twist UV Review

Resources, Recommended Reading:


Please reference this very in depth & researched article that is an IMPORTANT READ for anyone interested in moving from basic pond keeping to more advanced pond keeping:

Pond UV Sterilizer Use Beginner to Advanced

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Hot Cathode vs. Cold Cathode UV Bulb; Are Long Life, Easy Start UV Bulbs worth purchasing?


UV-C Hot Cathode Quartz Germicidal Lights/Bulbs

Long Life, Easy Start UV Bulbs; Are Cold Cathode, Low Output UV Lamps worth purchasing?
UV-C Bulb Problems

Updated 10/15/2020

First a little background information:

UV-C Hot Cathode Quartz Germicidal Lights/Bulbs are similar in their operation to the standard fluorescent lamps. The Hot Cathode lamp operates from a ballast or transformer and requires a device such as the glow bulb starter or electronic ballast to preheat the electrodes in order to start the lamp.

The electrodes, located at the ends of the lamp, are tungsten filaments coated with emission material and, under normal operation, govern the life of the lamp itself (not output).
Operation at low temperatures as found in many ponds in the Winter or early Spring may result in excessive lamp blackening and more rapid depreciation in ultraviolet output. As well, starting of the Hot Cathode lamps at low temperature may require a few minutes.
It is also noteworthy that the tungsten filament used in the High Output UV-C Hot Cathode Quartz Germicidal versus many cold cathode are more fragile and burn out more quickly, especially with many "starts".

Some high end Compact Hot Cathode Germicidal Lights/Bulbs such as those made for/by "American Aquarium" UV; G23, G11 have small metal pre-heat elements that aid in starting and reduce cold start times and wear and tear on the filament.

American Aquarium Lamp Resource: American Aquarium Products Compact UV Bulbs

Because of the voltage surge required by a Hot Cathode UV-C Bulb to light, ANY electronic ballast that is not providing this voltage due to age, damage, or simply poor quality, WILL fail to light a new Hot Cathode while this same ballast can still light an older hot cathode or a new cold cathode.

Hot cathodes generally achieve much higher power density than cold cathodes lamps and therefore produce more energy per given watt of energy used, making these a more desirable type of UV Bulb/Lamp for this reason alone.

Despite the shorter life, and requirement for optimum functioning ballast to light aside; these UV lamps produce an optimum UV-C at 254nm, which is what you need for proper sterilization!

smartpond 700-GPH Submersible Pump cold cathode UV bulb, lamp
Some manufacturers/retailers in an attempt to lure customers into thinking a cold cathode bulb is a the way to go just because of the longer lifespan are now incorporating these into UV pumps.
This Smartpond 700 gph not only utilizes these poor UVC emission UV bulb/lamps, they use a 2.5 watt bulb that even if the optimum low pressure, hot cathode UV lamp were used, it would fall far short of anything remotely effective as per the known science of UV Sterilization.
A Lowes web page even has some positive reviews for this product, but I can assure you that this is clearly the placebo effect as there is no way a 2.5 watt cold cathode UV lamp can provide any real results.

Similarly many products made in China are made to differing specifications depending upon what the retailer/distributor desires as a "price point".
This is VERY common with SunSun products where UV Sterilizers as well as canister aquarium and pond filters will come with ballasts only meant to fire low output UV bulbs/lamps. So when the owner purchases a higher output true UVC lamp, the bulb may not fire or burn out in short order due to difficulties firing these UV lamps.

UV Sterilizer Use, Facts & Information based on Experience and Research

As an example from the above referenced article, an optimal hot cathode low pressure 2.5 watt UV lamp would only provide Sterilization at 75 gph and true algae control at 125 gph. But this product does not even use this lamp and also has a poor flow pattern and less than optimal distance from the UV lamp inside the Sterilization chamber.
So a pump rated at 750 gph with this UV bulb/lamp is basically a pump with a pretty blue light decoration inside- DO NOT PURCHASE!!!

Cold cathode lamps have no thermionic emission coating to wear out and can have much longer lives than hot cathode thermionic emission tubes, however cold cathode lamps are less efficient than Hot Cathode lamps lamps because the cathode fall voltage is much higher (See Resources).

Many sellers of these lower price, longer life, cold cathode UV bulbs, claim these bulbs will provide longer life & easy/quick lamp starts often at a much lower price. Often these are sold at eBay and many "Top Bulb" or "Ushio" sellers that come up on Google's spammy algorithm.
What many of these sellers may not even realize (many probably do and choose to market these bulbs falsely), is that most of these bulbs are only actually intended as nail curing UV bulbs, NOT for use in true level one UV Sterilizers for pond or aquarium use!!

While this is true, these lamps/bulbs produce UV-C irradiation that can be as low as 185nm (which produces undesirable ozone) and as high as 330nm (which is UVB, not UVC).
With as little as 7% desirable UVC with these cold cathode, medium pressure UV bulbs; How is saving a few dollars and getting a few extra months life worth a bulb that is almost useless compared to a vastly superior Hot Cathode low pressure full UVC Bulb????

Obviously I am providing generalizations since these lights can vary, but what is clear is you are not achieving the optimum UV-C at 254nm.
As well, advertising 8000-10,000 hours of life is another dead giveaway that the lamp is NOT a High Output, Low Pressure Mercury Lamp since closer to 4000 hours is all you should expect for peak performance.
See:UV (UVC) Lamps/Bulbs used in Aquariums/Ponds and How they Work


Sadly many buyers are impressed by the "easy starts" and "low price" that these cold cathode UV Bulbs provide and the fact that these long life/low output UV Bulbs will often light in UV Sterilizers with worn ballasts that do not have the energy (voltage surge) to fire/start a new Hot Cathode Germicidal UV-C lamp/bulb.

Add to this problem that many UV Sterilizer ballasts degrade quickly (especially when used for ponds where more moisture is present) resulting in the un-informed user believing that their low end UV bulb is actually better than a a premium UV-C Hot Cathode Quartz Germicidal Light/Bulb when the OPPOSITE is the truth!
Even popular UV Sterilizers such as the over rated Turbo Twist has a high ballast degradation rate.

See: Potential UV Sterilizer Problems; Weak or Poor Quality Ballasts.

Purchasing a High Output 254nm UV-C Hot Cathode Germicidal Bulb for a UV with a weak/degraded ballast that will not light/fire a high output bulb, then purchasing a low output long life bulb that does work with this weak ballast is not an indicator of bulb quality, rather a lack of understanding of what makes a TRUE UVC producing lamp!!!

UV Bulb Resource: High Output Germicidal Bulbs

Unfortunately many manufacturers now even sell these almost useless for UVC sterilization cold cathode UV bulbs. As these will almost always light, and this allows for UV Sterilizers with a poor ballast designs that do not last long to appear to be functioning.
Worse yet, I have had customers/clients forward emails/letter claiming only their "original equipment" UV replacement bulbs should be used as their UV Sterilizers may not light the vastly superior hot cathode UV Bulbs.

The result, if a potential customer falls for this incorrect line of reasoning, is a UV Sterilizer that is almost a useless device as it is producing a fraction of the necessary UVC energy for level one or two sterilization or even clarification!
This is putting the blame in the wrong place, keeping a UV Sterilizer with a ballast that has degraded and then only using cold cathode UV Bulbs makes no sense at all; why have a UV Sterilizer that is only 7-15% effective??

Such is the case with this sarcastic email:
"If many manufacturers are using easy start bulbs to make up for so called "weak ballasts" then why does the website (selling hot cathode UVC Bulbs) say hot cathode bulbs are compatible with their units? They clearly are not compatible with the majority of units."

The logic here totally escapes me!!

  • First this is not true, I am speaking about degraded ballasts, as even a new Coralife will fire a hot cathode "True" UV-C bulb, but a degraded electronic ballast will not.
    Using the Coralife again as an example, my aquarium maintenance business has serviced many of these over the last decade, with a high quality UV C lamp working fine, but once the ballast degrades, only a cold cathode or 'old' (mostly expired) hot cathode will fire (it is noteworthy that the life span of a Coralife ballast is lower than many UVs). The FACTS are that these ARE compatible with the majority of unit, assuming a fully functional, non degraded electronic ballast/transformer.

  • Second; Such a comment shows a total lack of understanding of fluorescent ballasts.
    A magnetic ballast would not have such a problem, since these utilize a fluorescent starter to provide correct "surge" voltage to light the UV-C Bulb.
    However most UV Sterilizers/Clarifiers utilize electronic ballasts of which many have poor circuitry that is easily degraded, especially by moisture; Once this happens a hot cathode true UVC Bulb cannot light.
    See: Weak of Poor Quality Ballasts

  • Third; the UV-C bulbs I have used and sold in my professional endeavors of aquarium/pond design and maintenance do and have worked in the majority of units

  • Forth; (and I will repeat myself), why would you want a UV Sterilizer that only makes a "pretty blue light" that is about 7-15% effective for UV Sterilization??

See also: Electronic UV Sterilizer Ballasts; Lamp Problems

The bottom line is do not be fooled either by the low price, long life claims, or ease of lighting (or lighting at all with a weak ballast) of these long life/easy start UV Bulbs, as these are not the reason you should be purchasing a replacement UV Bulb.
Your UV Sterilizer is meant for Sterilization (not a pretty "blue" light) and this will NOT be achieved with these low output UV bulbs (especially level 2 sterilization)!!

Unfortunately some manufactures utilize low output UV bulbs such as Hagen Laguna; these UV bulbs are very inferior to high output UV bulbs and the result is no Level One UV Sterilization and even poor Green Water control.

For further resources see these articles:

*UV Sterilization; Facts & Myths
*UV Bulb Troubleshooting Guide

For the Best Very Best UV Sterilizer for your Pond or Aquarium:

AAP Advantage & Vecton Premium UV Sterilizer

There is not any better UV Sterilizer for both durability and UV-C irradiation effectiveness than the AAP Advantage and Vecton UV Sterilizer line, at any price!

Further Reading of Interest:
Aquarium Disease Prevention
AQUARIUM DISEASE PREVENTION; Steps to a Healthy Aquarium & Sick Fish

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Correct UV Sterilizer/Clarifier Applications


TMC Pond Advantage, Aquarium Vecton UV Sterilizer, ClarifierI often get questions or even complaints about the use of UV Sterilizers/Clarifiers for Aquariums & Ponds.
I will answer a couple of questions that indicate the improper of UV Sterilization for Ponds or Aquariums.

Indepth Information on UV Sterilization:http://www.americanaquariumproducts.com/AquariumUVSterilization.html

Updated 9/24/13

(1) Question; "My Pond turns pea soup green as soon as my UV Sterilizer UV-C Bulb burns out or is removed"

Answer; This certainly shows that you have a correctly installed and functional UV Clarifier.
However this also tells me that you depend too much on your UV Clarifier/Sterilizer as although I certainly recommend these devices, a pond keeper should not have a system that is all or nothing as per the UV Clarifier.

I strongly suggest increasing filtration, especially bio filtration that removes many of the nutrients necessary for an algae bloom.
A Bio Falls Filter (either purchased or DIY), a Pressurized Pond Filter can either be added or even duplicated.
Pond Veggie FilterAnother type of Filter I set up in over 90% of my ponds is the "Veggie Filter". Properly constructed, these plant filters can really "scrub" many nutrients otherwise utilized by free floating algae.

I have found in ponds with good mechanical/bio filters such as a Pressurized Pond filter along with a Veggie Filter rarely got overly green in summer when the UV Clarifier was disconnected or broken down.

For further information about pond veggie filters, please see:
DIY Veggie, Plant Filters.

Sources for Pond Pressurized Filters & UVs:
UV Pond and Aquarium Clarifiers
Pressurized Pond Filter

(2) Question: "I have been told a UV Sterilizer does not really help a saltwater or freshwater aquarium other than clarity. I did not see any difference than this when I added a 9 Watt UV Sterilizer to my aquarium sump (a pump rated at 900 gph)"

Answer: This answer is much more complex than the last, so I will first state that a thorough reading of this blog and even more the UV Sterilization article below should be done:
"UV Sterilization; Facts and Myths"

A few points: First of all, 900 gallons per hour is much too fast for a 9 Watt UV to perform Sterilization, and likely little clarification either.
*Many persons who slam UV Sterilizers for aquarium use, have them incorrectly installed or are utilizing Sterilizer/Clarifier devices of poor quality for anything other than clarification, such as the Green Killing Machine".
Please see: UV Equipment to Avoid

Here are three parameters required for effective UV Sterilization that are often missed:

  • Flow Rate; this should be 45-60 gph per watt for Clarification, 20-35 gph per watt for level 1 Sterilization, & 8-12 gph per watt for level 2 Sterilization.
    For more in depth exposure time information, please see “UV Sterilization; UVC Penetration (Microwatts second/cm2)”.
    See the sections dealing with UV-C Penetration gives a more detailed explanation of the time required to kill pathogens based on wattage & distance for the UV-C source.
    For example the bacteria Vibrio requires a UVC exposure of 6500 mW/cm2 or more, this means an exposure time of 5.68 seconds for a 9 watt UV lamp is required to kill this pathogen.

  • Aquarium (or Pond) Turnover rate; this should be Once per 2-3 hours for Clarification, 1.5 times per hour for level 1 Sterilization, & Up to 4 times per hour for level 2 Sterilization

  • UV-C Penetration; in simple terms this is often a problem with the equipment itself with too much distance from the bulb to the outer wall of water containment resulting in much of the water not being properly irradiated even with proper flow rate or turnover rate.
    Examples are Canister/Pressurized filters equipped with built in UV-C Lamps, internal UVs such as the before noted Submariner/Killing machine, or even otherwise good UVs with baffles to slow water flow but in turn keep much of the water at too great a distance form the UV-C Irradiation.

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Aquarium UV Sterilizer Combinations


Aquarium UV Sterilizer Ideas; Part Two

Updated 9/21/13

In part one about 18 months ago I noted using intake and return adapters as another way to connect UV Sterilizers to aquariums, especially smaller aquariums where the use of more traditional set ups such as canister filter or sumps is not possible.
In this article I will expand on this idea and as well note some problems with many sump set ups and with the growing popularity of internal UV Sterilizers, which although they make work, they are prone to leak problems that usually result in a short lifespan.

First I will start with the use of power heads, pumps, or Internal Filters (which is my first choice do to pre filtration of water allowing for a more effective UV Sterilizer).

Aquarium UV installation diagram with Internal Filter or Power head
Here is a basic picture for plumbing a compact UV Sterilizer using an Internal Filter or Power Head. The lines and UV can be more neat than the diagram shows (this is just for emphasis). This demonstration is shown on the front of the tank for easier viewing, obviously this would be placed on the back of an aquarium.
You may also place your power head/ internal filter on its side for an easier tubing application.
The picture can be enlarged by clicking on it too!

The advantage of this set up is that it allows a small (or larger aquarium) that may only have a HOB filter such as a Whisper to also have a UV Sterilizer PLUS more filtration and filter redundancy.
In all bluntness, this type of set up is not all that expensive when you consider the costs of fish and medications or simply piece of mind that a UV Sterilizer can provide in improving water quality (such as Redox) and lower water borne disease incidence. This is not to say that a UV Sterilizer will solve all your problems, but they are often a major piece of the good water parameter puzzle and in my experience should be included in most aquarium set ups if at all possible.
Please see this article for more why:
UV Sterilization; How UV Sterilizers Work

Compact UV Sterilizer kit with Internal Filter

Here is a picture of an inexpensive set up that is ready to go for an aquarium as small as a 10 gallon aquarium, as well as a set up with a 9 watt Compact UV that would easily work for a 100 gallon aquarium.

Please follow this link for more information about these kits:
Terminator UV Sterilizers/Filter Kits

Please click pictures to enlarge or visit website

Similar to the above ideas, many UV Sterilizers, such as the Custom UV Sterilizer pictured to the left, can be hung on the back and then connected to an Internal Filter such as the SunSun Internal Filter or other similar Internal Filters for a simple UV application, especially when a canister filter is not available or practical (or even desired).


A popular use of UV Sterilizers is in the sumps of high flow sump systems of large aquariums (especially marine), unfortunately the majority that I have seen when called out on service calls were installed improperly often resulting in the owner of the system to pronounce the UV Sterilizer a "failure" when in actuality the flow rate was way to fast for the UV Sterilizer wattage installed. As a generalization it is best to have a flow rate of under 20-30 gph per watt for a UV to be effective for bacteria, Redox, algae (slower yet for parasites) This flow rate can vary based on many factors that I will go into here (I recommend reading the link earlier in this article for more on this subject), I will only state that although you do not need to pay a fortune for a UV Sterilizer, most of the units selling for under $50 are junk and even a few name brands selling for over $100 are not delivering what you pay for.

UV T valve diverter for high flow pumps
UV Sterilizer Diverter Valves are the answer to most high flow pump problems.
For use with ponds, sumps, or any high flow water application where the flow rate exceeds the recommended GPH per watt so as to divert/bypass some of the water around the UV Sterilizer.

See this site for more: UV Sterilizer Diverter Valves


With the above kit or similar in mind, please be careful of the relatively new Internal/Submersible UV Sterilizers sold under a couple of brand names (same design) BUT REJECTED by several wholesalers and retailers due to the fact that they tend to leak internally damaging and destroying the electrical components of the Unit often resulting in complete failure in under a year.

As well, while these UV Sterilizers did perform a good job at clearing "green water"/Clarification (while functioning), in tests these UVs did a poor job of performing Stage One Sterilization due to flow pattern and distance from the UV Bulb/Lamp inside the unit. Level one (stage one) UV Sterilization is essential if you would like to step up in Aquarium or Pond Disease prevention by not only killing disease pathogens, but improve Aquarium Redox which also in turn improves fish health by improving fish immune response.

More information & products:
*Levels of UV Sterilization
*Aquarium Redox
*Replacement UV Bulb/Lamp

I personally rejected these units (The Green Killing Machine) after Kokaho Aquarium and other users of these Internal/Submersible UV Sterilizers found total failure of most or all of them within a year or often much sooner.
What is even worse is that a manufacturer of the most popular of these internal UVs had someone spam my YouTube video demonstration of how to install a custom UV on an aquarium using Internal Filters.
I then commented on their clear attempt to push this product that I in good conscience could not recommend (in fact I noted in my comment that it was an awesome idea, which it is, but failed in practicality).
They had the audacity to call ME unprofessional implying that I had gone to their Video when in fact that were trying to peddle their product via a comment on my video.
They also ended up with name calling when they could not change my mind stating that "I needed help".

Honestly in my opinion this is an act of desperation by a company that may have a good concept, but is failing to sell many due to the fact that many in this industry but for a few less than honest retailers refuse to stock these Internal UV Sterilizers (or "algae/green killing machines").
In the case of internal UV Sterilizers I would have loved for these to work, as I think this is a good idea, but I cannot honestly sell something that I know has flaws that will lead to product failure somewhere down the road as well as not being a true UV Sterilizer, rather just a water clarification device.

If this idea appeals to you, avoid the before mentioned Submersible UVs along with similar models such as the Submariner sold at PetCo, Amazon, TruAqua and elsewhere and give the only one of a couple Submersible UVs I have found to be both reliable and able to actually provide level one UV Sterilization.
SunSun CUP series

See this Review from this website:
Submersible UV Sterilizer/Clarifier Review; Killing Machine, more

Please read this article about the use of UV Sterilizers for a Researched and regularly updated information. No advanced aquarium keeper should consider their knowledge complete until they have read this content, including the cited references such as about Aquarium Redox:


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UV Sterilizer Questions/Myths Answered for Pond & Reef Aquarium


Updated 4-6-19

More UV Sterilizer Questions/Myths Answered

In this post I will answer two questions (or possibly “myths”) about the use of UV Sterilizer in Aquariums and Ponds based on email and phone questions I often get.

Myths versus facts in UV Sterilizer use, aquarium or pond
The questions are:

• Filter placement in relation to UV Sterilizer in ponds.
• Danger of UV Sterilizers to copepods in reef aquariums.

Another article on sterilization in ponds:
Pond Care Information


(1) Question: Is the UV best placed after or before a filter in a pond?

This question is myth based as there are valid reasons for both applications.
However based on my own use and controlled tests using UV Sterilizers with filters before, after, or not at all, the answer of using the UV Sterilizer after the filter is the better choice.

Let me explain further; when a UV Sterilizer/Clarifier is placed BEFORE a pond filter with no pre-filtration, you do catch “clumped” algae coming from the UV Sterilizer.
This is even more noteworthy when a UV is run a flow rate over 30-35 gph per watt as this higher flow rate will generally not kill algae outright, rather “clump” the algae where it will be expelled from the UV Sterilizer into the pond water column.
Otherwise, this "clumped algae" then it either falls to the bottom of the pond becoming part of the organic mulm/detritus and/or may be picked up by any existing pond pump and filter and removed.

This is the ONLY reason to place a filter after a UV Sterilizer in pond applications.

With previous paragraph in mind, the generally better way to utilize a filter with a UV Sterilizer is to place the filter prior to the UV Sterilizer.
The reason is that turbidity in the water will lower UV Sterilizer effectiveness, and sometimes (based on my tests) to levels that render the UV Sterilizer ineffective.
This often results in the misinformed comment that UV Sterilizers do not work (based on emails and phone calls).

Pre-filtering the water prior to entering the Ultraviolet Sterilizer improves the function of UV Sterilizer by trapping larger particulates, thus allowing more of the UVC irradiation to reach the algae that is causing green water (this also improves destruction of disease pathogens at lower flow rates in both aquariums and ponds).

High Output UV Lamps for aquarium, pond
The other reason for pre-filtration of pond water is I have often have had success in initial clarification of pond water with no pre-filtration, but over time (& sometimes only a few weeks), sludge will build up in the UV Sterilizer.
Often this sludge builds up in recesses around the UV Bulb or quartz sleeve, rendering the UV Sterilizer/Clarifier useless.
This does not mean that pre-filtration does not prevent sludge from building, as it does not, but it most definitely slows down the accumulation of sludge, as well the time it takes to buildup sludge in your pond UV Sterilizer depends on water turbidity, algae, bio load and obviously the quality of your pre-filter.

Where to get:
UV Bulbs; Premium High Efficiency (not the low output UV lamps commonly sold on Amazon or eBay)
Quartz Sleeves
Pond UV Sterilizers

I should note that having both a pre-filter and a post filter (such as a DIY Bio falls or similar filter that fits into the water return prior to re-entering the pond) would be an excellent combination.

(2) Question: Will a UV Sterilizer kill off my beneficial copepod & other crustaceans colonies in my reef tank?

Although not as common a question as the previous question, it still crops up from time to time and I have much harder time understanding why otherwise quite advanced reef keeper fall for what amounts to a UV Sterilizer myth.

As well, my controlled studies admittedly did not include exact counts of copepods with different levels of UV Sterilization, it did show that copepod colonies when properly established never diminished with UV Sterilizer use in reef tanks.
Study Reference:UV Sterilization Studies

There is simple explanation for this result; that is most copepods do not occupy the water column in a healthy colony.

What is a healthy colony?
This is a matter of opinion or experience, but from my perspective a healthy colony is “housed” in large piles of live rock crumbles where many fish such as Mandarin Gobies will seek them out.
As well if you are using a Refugium and want to be certain that all of the copepods/ crustaceans that spill out into the aquarium are not killed, then be sure your UV is on its own filter/pump and not returning water to the aquarium using the same return line as the Refugium.
Finally whenever you dose your aquarium with certain live products such as live planktonic algae or infusoria, you should turn off the UV sterilizer or use a timer that is tied to certain cycles or automatic dosing.

Ocean Clear Aquarium Filter My final comment to this amounts to another aquarium keeping myth.
That is I have had clients/customers that have stood by this myth describe or show me their filter system and I have seen (or had them describe) several of these filter systems that employ micron filters (such as the Ocean Clear) that can easily trap copepods in their micron filters much more effectively than a UV Sterilizer can kill copepods.
In particular adult copepods for which a UV Sterilizer would have to run well under 10 gph per watt to have any chance of destroying any “pods” that get caught in the sterilizer.

As well pre-filtration which should be used in any UV Sterilizer application will trap most adult copepods from entering the Sterilizer.
What makes me laugh here is that these same aquarists often had healthy copepod colonies with the use of these Micron Filters.
I would explain to them that if these filters did not destroy their “pod” colonies, a UV Sterilizer would not either!
I should note that I am not against the use of these micron filters; in fact I think are excellent compliments to other aquarium filters, live rock, and healthy deep sand beds.

Please see this article for more about UV Sterilization and how it works:

UV Sterilization

Recommended Reading:
Common Aquarium Keeping Myths
Common Aquarium Keeping Myths

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UVC Irradiation and Immune Response, Aquarium Applications

UVC irradiation and immune response
This includes human research into BioPhotonic Therapy and UVBI Therapy

Updated 12/8/14

This article/post is meant to expand on my previous article “Fish Immune System and UV Sterilization”. This time utilizing information about UVC irradiation as per human studies and its affect on disease treatment and over all aquatic health.
While the application to fish in aquariums/ponds is somewhat “apples to oranges” in comparison at this point in time, the implications are certainly far reaching as to the affect on Aquatic Redox and fish health.

Since most in depth research is found in human studies due to the costs involved vs. lack of funding in the aquarium keeping hobby as well as the unfortunately common anecdotal comments made about UV Sterilization made by many in the aquarium hobby that are years behind real research; one often needs to go outside the hobby to find good and cutting edge research. In fact I just recently came across this gem of a post of anecdotal bad information from an otherwise good aquatic article: “For me, a UV filter is just a ‘feel good’ device and leads hobbyists into a false sense of security” It is too bad that so many aquarium keepers simply refuse to do their homework, but this is likely to continue considering how lazy many persons can be at times (otherwise how can you explain the popularity of such terrible sites for aquatic information such as Yahoo Answers among many others, or directories such as DMOZ with its outdated directories).

The concept of BioPhotonic Therapy and UVBI Therapy was brought to my attention in an email and phone call by a researcher (Dr. Mamoon Kundi) who found me via my UV and Redox research articles.
One concept is clear and that is that the use of >UVC lamps can affect both the oxidizing and reducing side of the Redox Balance equation that is so important for life.
Information on Redox

Studies in UV Irradiation

 BioPhotonic, UVBI Therapy  DeviceIn these studies, blood is irradiated (via different methods), often with very pronounced results. William Campbell Douglass, MD, who treats his patients using only alternatives and has written several books on these subjects, wrote a book called Into the Light, where he recommends Photoluminescence Therapy for the following conditions:
• Immune deficiency problems
• Viral Infections (hepatitis, respiratory, etc.)
• Pneumonia
• Non-healing wounds and wound infections
• Emphysema
• Inflammatory Processes: fibrositis (inflammation of, mainly, the muscle sheath), bursitis, iritis (inflammation of the iris), pancreatitis, etc
• Autoimmune diseases: rheumatoid arthritis, AIDS, etc.
• Osteomyelitis (bacterial infection of the bone marrow)
• Septicemia (virulent infection of the blood)
• Cancer (experimental at present)
• Peripheral vascular disease
• Most vascular disease
• Thrombophlebitis (inflammation of a blood vessel that results in blood clots)

Implications of this research as per aquariums/ponds
While we as aquarium and pond keepers are not too likely to utilize these UV blood irradiation therapies on our fish, this still has implications as to how a UV Sterilizer can be an important part of ANY aquarium keeper’s (or pond keeper) filtration system in that this latest research backs up many of my own tests and research going back to the early 1990s. The implications of the affect of the UV irradiation on how it may not necessarily outright kill pathogenic microbes found in the water column, however it certainly allows for an improved fish immune system response to pathogens, which is one of my earlier findings as well (although I did not know the whys of my test results back then). The affect of UVC irradiation also has a positive affect on Aquarium Redox Balance which is also important for aquatic health.

It is also noteworthy that even with regular water changes, and the addition of mineral cations that both replenish the electrolytes from the reducing side of the equation, this is only a part of what the human studies indicate, and that is while the use of minerals and other antioxidants is certainly a good idea, when there are stressors such as disease pathogens, immune deficiency problems, etc. there is a need for additional ongoing Redox Reduction to counter free radicals that a UV Sterilizer provides that mineral cations cannot provide adequately.

The bottom line is this is just one more piece of evidence that a correctly installed UV Sterilizer should be part of every serious aquarist filtration system, especially those who keep expensive, rare, or delicate fish.

Please read or at least glance over these referenced articles (more to come too):


As well as my UV Sterilization Article
& Aquarium Redox

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UVC, Watts, Microwatts


Revised: 1/2/18

UVC, Watts, Microwatts, Joules, & Light Penetration

This article/post is intended to give some basic understanding between the relationship of watts, microwatts, joules of UVC energy and how this translates to UV Sterilizer effectiveness.

Please keep in mind that the diagram in this article is based on air penetration, so some extrapolation is necessary for use in water applications (which is the primary intention of this article, although the principles apply to UVC air sterilization devices as well)
UVC Air Sterilization Devices

What is a Watt/Microwatt?

One Joule of energy = 1,000 milliWatt seconds = 1,000,000 microWatt seconds
One joule is the amount of energy required to perform the following actions:

• The work done by a force of one newton traveling through a distance of one meter (a newton is the unit of force equal to the amount of force required to accelerate a mass of one kilogram at a rate of one meter per second per second);
• The work required to move an electric charge of one coulomb* (the amount of electric charge transported by a current of 1 ampere in 1 second) through an electrical potential difference of one volt; or one coulomb volt, with the symbol C•V;
• The work done to produce power of one watt continuously for one second; or one watt second (compare kilowatt hour), with the symbol W•s. Thus a kilowatt hour is 3,600,000 joules or 3.6 megajoules;
• The kinetic energy of a 2 kg mass moving at a velocity of 1 m/s. The energy is linear in the mass but quadratic in the velocity, being given by E = ½mv²;
we measure UV-C intensity in Micro-Watts that strike one square centimeter of surface area.
Reference: What is a coulomb?


UVC Penetration;
A quote from an advanced sterilization article:
UV Sterilization; How a UV Sterilizer Works

"The emission or light intensity of a UVC germicidal light bulb is usually expressed in a term called "microwatts per square centimeter" (Mw/cm2). The maximum intensity provided by a single UV-C Bulb is at its surface.
So, if we calculate the surface area of the UVC lamp and only use that area which effectively emits UVC light rays, the effective area of UVC transmission will be established. Basic mathematics will show that the surface area of a cylindrical tube is ‘pie’ D L.

Next extrapolate this effective area of UVC transmission as having a screen with squares 1 centimeter in size. Each of these cm2 areas now, for measurement purposes, emits a UVC lamp intensity measured in microwatts, in other words; the term microwatts/cm2. UVC light intensity decreasingly varies as the distance from the UVC light increases.

Put more simply (a non scientific analogy); The amount of wattage will also increase penetration, as a higher watt UV-C bulb will generally have more Mw/cm2."

See this product link for high output Straight Tube UV Bulbs:
Premium HO Straight Tube UV Lamps

"In my own experiments I have used 15 watt and 25 watt UVC bulbs in exactly the same unit (both were 18”), if wattage were only considered there would be a 60% increase in effectiveness, however I only observed a about a 25% increase.
When I used a 30 Watt UVC bulb in a unit with over twice the exposure as the 15 Watt, the kill rate more than doubled. From my experience, if you increase wattage (and Mw/cm2) you need to also increase the volume of water to maximize the higher watt bulb.
Experiments can also be safely conducted with standard household light bulbs to correlate penetration. For this start with a 7 watt clear bulb (such as a Christmas bulb) and place varying thicknesses of paper/ cardboard in front of the bulb and measure when penetration stops. Continue this with higher and higher wattage bulbs."

UVC Intensity, UV Sterilizer The Diagram to the left can give a rough comparison of distance as per UVC energy as expressed by MW/cm2 in Air transmission.
The dose applied by an UV-C lamp installation is a function of the lamp output, the intensity factor, and time. As an equation; Intensity x Exposure time= microwatt seconds/cm2.

As an example, a 9 watt UVC lamp at one inch from the lamp is found by this formula:
9 x 127 = 1143 mW/cm2.
Since many bacteria such as Vibrio require a UVC exposure of 6500 mW/cm2 or more, this means an exposure time of 5.68 seconds is required to kill this pathogen

Now let me point out that even though I have published this diagram, please use this as a rough guide only, as I have found inaccuracies in it. To be more blunt; I have found the distance, wattage, and flow rate to be the MOST IMPORTANT factors in determining exposure/effectiveness. This diagram is STATIC and does NOT take into consideration the dynamics of UVC radiation penetration for which I have yet to find a good formula to demonstrate this (even in University studies).

What is often missing in any equations I have seen is the dynamics of water flow geometry, actual water flow, and wattage. The bottom line is to use this table and others you might find elsewhere with “a grain of salt” noting that these are static and even then are flawed when true output via wattage is taken into consideration.

Further Reading, References, Product Resources:

*UV Sterilization; How it works for Aquariums, Ponds, & more

*Harmful Pathogens: The Threat, mJ/cm2


Aquarium UV Sterilizer Experts for lamps, bulbs
UV Bulb; Replacement Lamps

The very best UV Replacement Lamps/Bulbs at competitive prices!

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UV Sterilizers and Bio Cube Aquariums or Internal Wet/Dry Bio Filters


Updated 9/24/13

The Bio Cube Aquarium is a popular style of aquarium nowadays, although I have to laugh a little here as these are highly touted as a new way to keep small marine reef aquariums or planted freshwater aquariums while in reality the basic built- wet/dry filter system is nothing new to the hobby and in fact there is a new Internal Wet/Dry Bio Filter (made by the same manufacturer in China) that is less than half the cost of many Bio Cube Aquariums WITH the cost of an aquarium.
Product Link:

The ReSun BF 100 is the exact same filter/pump and can be used in (for example) a 20 gallon aquarium to turn it into a Bio Cube style aquarium.
The addition of good lighting such as CFL/SHO, T2, or LED Lights are also necessary for a "higher end" or advanced aquarium.

For more information on these lights, please see:
With a ReSun BF100 and your own aquarium set up the cost is often lower than many of the larger bio cube aquariums.

Anyway, the other point of this article/post is to point out that whether you use a Bio Cube Aquarium or a ReSun BF Wet/Dry Bio Filter, both of these filters systems lend themselves nicely (& easily) to a simple UV Sterilizer set up unlike say a HOB ("Hang on the back", Aquarium Power Filter) filter set up.
The advantage of a Bio Cube/BF 100 is that you can add a UV Sterilizer too. Not only lower the incidence of diseases, but just as importantly (or maybe more importantly) improve Aquarium Redox and improve fish disease resistance.
Aquarium Redox Reference Link:

This is easily achieved by simply purchasing additional 1/2 to 5/8 inch ID tubing and running this tubing out of the aquarium to a UV Sterilizer (a 7 watt Terminator is pictured in the diagrams) and then inserting the return tubing back into the return slot on your BF 100 or Bio Cube Aquarium.
See this product link: 7 watt Terminator UV Sterilizer

Please click on pictures below for a better view
Bio Cube Aquarium with UV Sterilizer This picture shows a 5 Watt Terminator UV Sterilizer connected to a 14 gallon Bio Cube Aquarium.
You can see how the tubing simply comes out of the aquarium slots in the back of the aquarium (the slots can also be enlarged with a keyhole saw) and that the UV Sterilizer hangs easily on the back. My suggestion for most Bio Cube aquariums is a 5, 7, or 9 Watt UV Sterilizer.

Internal Wet-Dry Bio Filter with UV Sterilizer This picture shows the simple mounting of a ReSun BF 200 with a Terminator 5 Watt UV Sterilizer. As with the Bio Cube application the way you add tubing is quite straight forward and as well the 5 and 9 Watt Compact UVs or the High Performance TMC 8 Watt Vecton UV Sterilizer would also be my suggestion (the Vecton is an excellent choice for those desiring a UV Sterilizer that is second to none in Sterilization abilities & reliability).

As a final note, for maximum UV Sterilizer efficiency, it is important to change your UV Bulb every six months.
See this product link for premium hot cathode, low pressure UV Replacement bulbs:

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Fish Immune Health and UV Sterilizers


Updated 3-10-19

Fish Immune System (Including Anti-inflammatory), Redox, Oxidation, and UV Sterilization

UV Sterilizers, Terminator, Custom, Gamma

I have seen many comments posted in various places on the internet claiming that running a UV Sterilizer 24/7 will weaken the immune system in fish in part by creating a sterile environment.
I have tried to find more information as to how this myth got its start and the best I can come up with is that many are equating UVC radiation (emitted in UV Sterilizers) to Ozone produced by Ozone Generators.


Aquarium Ozone GeneratorFirst even though I have not found an Ozone Generator as effective as most UV Sterilizers for disease control (& Redox), even then when properly used the Ozone is not added to the aquarium.
However more importantly is that a UV Sterilizer keeps ALL UVC irradiation inside the unit and this reaction actually breaks apart free radicals and other oxidizers such as Ozone (similar to the reaction of Ozone and UV light energy in the upper atmosphere of Earth).

What is most important to note is that a properly installed UV Sterilizer will IMPROVE a fish’ immune system by creating a better Reducing Redox environment in the aquarium after water has passed through the sterilizer (providing it is a reasonably good unit such as the TMC Vecton/ Advantage UV Sterilizer, the AAP/SunSun Quality Compacts or other higher efficiency, UV Sterilizers.

See these product resource links:
*AAP/TMC Premium High Dwell Time UV Sterilizers for Aquarium & Ponds(Category A)
*AAP Compact UV Sterilizers/Clarifier (Category B)
*TMC Next Generation Ozone Generator from AAP

Here is a quote from "Aquarium Redox Potential":
"A proper Redox Potential improves the health of humans AND fish. A Redox Potential in the +125 to -200 mV range in human studies has been shown to have the same affect as anti-oxidant preparations such Vitamin C".
As well, a Category A or B UV Sterilizer improves Redox Balance via COSTANT removal of oxidizers in the water column thus DIRECTLT lowering oxidative stress in fish.

This picture of a controlled test where by an oxidizer (Potassium Permanganate) is added to the water demonstrates this ability. The control tank retains the color of the Potassium Permanganate much longer than the tank with just Category B UV Sterilization ('Category A' Sterilization will clear it even quicker, although few aquarium/pond UVs are 'Category A' any more with the AAP Vecton/Advantage one of only a couple of brands):

Aquarium UV Sterilizer lowering oxidative stress in fish

In medical studies the enhanced oxidizing environment can facilitate the binding of pathogens or antigens to effector cells (a type of lymphocyte that are actively engaged in secreting antibodies) leading to a hyper-responsive innate immune system.
Previous work has shown that an oxidizing environment leads to enhanced release of super-oxide and nitric oxide, activation and translocation of nuclear transcription factor and enhanced production of cytokines (proteins and peptides that are signaling compounds produced by animal cells to communicate with one another). The creation of a markedly reduced environment by addition of antioxidants blunts all of the above primary responses of the innate immune system."

In studies using human blood therapy, the use of UVC to irradiate blood, these are just a few of the findings:
*Improved circulation and oxygenation of tissues
*Anti-inflammatory effects
*Stimulation of the Immune System
*Increased Tolerance of the body to Chemotherapy and Radiation
*Cardiovascular protection
*Powerful Anti-Infection Properties
See this article for more: Oxygen Healing Therapies with UVC

It should also be noted that a True UV Sterilizer cannot create a sterile environment as it cannot reach all aspects of the aquarium such as gravel, filter media, and the fish internally!

It is unfortunate that these false statements are still widely circulated, I recommend reading this article about UV Sterilization for more:
Ultraviolet Sterilization in Aquariums and Ponds

Or this article about Aquarium Redox:
Aquarium Redox Potential

Or even this article about Aquarium Calcium, GH, KH, pH (as this is also an important aspect as well to a healthy fish immune system):

Finally, if you have a properly set-up aquarium or pond UV Sterilizer, it is important that you change your UV-C Bulb once per six months for most aquarium applications and once per year for most pond application (six months in warm year round ponds).
See this High output UVC bulb product resource link: PREMIUM High Output UV Lamps/Bulbs for Aquarium/Pond

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