# UV sterilizers



## Sinister-Kisses (Jul 19, 2013)

Does anyone use these in their tanks? I know they're supposed to have a few benefits in an aquarium, but specifically I'm wondering whether they really DO help reduce algae in a tank. My mbuna tank is a 40 long, and the rocks in it go about halfway up the tank - so there isn't much space between the rocks and the LED light over them. As such, the brown algae builds up very quickly on the rocks, even though I make sure to keep lights on to a minimum - usually about 5 or so hours a day. I've tried fussing with other lights that aren't as strong, but they're just too dark and the fish get lost. As it is, I have about an 18" LED as the only light on a 48" in tank, and I've used black electrical tape to cover up half the lights on the fixture. I manually scrub the rocks every week with a water change, but it grows back so **** quickly lol. So I'm wondering if the claims that UV sterilizers help reduce algae have any merit or not?


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## SenorStrum (Aug 14, 2020)

I guess I'm supposed to say *Bump* here...?

I also would like to know about FW UV Sterilizers. Like almost all things in the fishkeeping hobby, it looks like the saltwater guys have us beat here with technology, research, advice. 
My wife and I have been wrestling with whether or not to include one on the Mbuna tank. So, does anybody run one on their tanks? Some folks in the hobby have told me it's a waste of money and others have said it's dumb not to do it. I'll confess, I've always been "Dumb" in this case.


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## fishboy75 (Jan 16, 2020)

I used one about 20 years ago on a 180 community tank I had. I was living at home rent free and had extra money to splurge at the time. My experience is it won't get rid of any algae that is growing on the glass, rocks, etc and is only useful to eradicate an algae bloom. It will eliminate any free swimming parasites that pass through. If you are medicating the tank the UV needs to be turned off as it could affect the medication being used. The bulbs usually last only 6 months to a year. Don't remember the cost of a replacement but also know I was too lazy or not as diligent in my early twenties to keep up with the maintenance of the sterilizer or the tank for that matter. I would bet there are more people that don't use them on freshwater tanks than do. My opinion is they aren't necessary for sure but I would do more research as my opinion is from 20 plus years ago haha.


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## Toby_ (Feb 15, 2021)

Good input above...

Also years ago, I used them when breeding fish that were prone to parasitic infection. They helped a ton with that concern.

As mentioned, the bulbs have to be replaced often. I had some that said 6 months, others that said a year. I generally went with the manufacturers recommendation. That said, they don't stop working all of a sudden. They potency erodes over time. The stronger the thing youre trying to kill, the less erosion you can get away with. So a "middle aged" bulb may work against algae that won't work against parasites. Thus, you can push the envelope.

Remember, slow flow rates through these things are essential.

I used to have a 250 gph Magnum Hang On Tank canister, loaded with filter floss and a water polishing cartridge (dense media slowed water considerably) that ushed water through a 9W Turbo Twist light. This was a very effective combination.

As mentioned, a UV light will only kill algae that goes through the light. It won't kill whats growing on the rocks, substrate, etc. That said, I had less algae growing in my tanks that used UV lights vs the ones without. Back then I used to often fight with cyanobacteria and UV lights helped a lot with that.


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## Stu W2 (Nov 17, 2020)

In my experience they will not kill established algae. By established I mean growing on hard surfaces. I think of these devices more as ways to minimize parasites, bacteria etc. rather than for any other purpose. To that end I'm a believer in their usage.

Regards,
Stu
PS: Depending upon the models used you can find replacement bulbs at such outlets as Home Depot at a fraction of the cost of those fancy name brand bulbs sold at LFS.
PPS: My brother uses two large ones on his koi pond and swears by their ability to control algae blooms.


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## SenorStrum (Aug 14, 2020)

Since my bump post (Which I had forgotten about) I've done a ton of research. I've now become a firm believer in UV sterilizers and run them on all tanks wherein they are practical. Full time.

A few things about Sterilizers. 
1. You don't have to run a big or expensive one. Because of the reciprocity rule in photobiology (Bunsen-Roscoe law), each pass through a sterilizer counts. Running it on a closed loop means that the organism passes through multiple times (As opposed to a pond) so a MUCH smaller device can be used. Please be aware that folks who sell them do not know this and will tell you you need one which is hundreds of watts. I believe this is profit motive.

2. They are a simple machine and cheap is fine. There is absolutely no reason to go with a more expensive one; they all use the same bulbs. Same bulb, same light, same effect.

3. They only sterilize things that pass through them. Algae spores that pass through will not settle on rocks and bloom. Anything that does not pass through, will. Also, algae will continue growing on rocks. Note here: I did notice an overnight difference in water clarity and the rate at which algae settles on the rocks.

4. I have been aggressively acquiring and quarantining fish and have had some disease in my tanks, but no "outbreak" or transmission to other fish on tanks where I have a sterilizer. I have lost half the fish in one tank where I do not have one.

5. flow rate doesn't matter. Total time exposed to the light matters. See number 1.


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## Stu W2 (Nov 17, 2020)

Hello SenorStrum,

Thank you for your post. That information is good to know.

Regards,
Stu


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## Idech (Nov 8, 2020)

If you decide to get one and you have a Fluval canister filter, Fluval has a nice one that came out this last year. It's bulb will last almost the lifetime of the tank, contrary to other UV lights that need expensive bulb replacement frequently.


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## Stu W2 (Nov 17, 2020)

Hello Idech,

Is this the one to which you refer?


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## Idech (Nov 8, 2020)

Stu W2 said:


> Hello Idech,
> 
> Is this the one to which you refer?


Yes, absolutely ! I'm planning on getting one eventually.


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## Stu W2 (Nov 17, 2020)

I've located the following on the Internet (Aquarium Store Depot reviews) and found it sufficiently thought provoking to provide it here for others to review for educational purposes.

"UV Sterilizer Levels - Not All Are Created Equal
Knowing the sterilization levels a unit can achieve is what you need to know as a consumer in order to purchase the best uv sterilizer for your fish tank or pond. We can break down UV sterilization into 3 uses.

Green Water Clarification (Clarification)
Bacterial, Flagellates, and Light Parasite Sterilization (Sterilization) 
Heavy Parasite Sterilization (Heavy Sterilization)
The best sterilizers on the market can do the 3rd category. The middle grade models can do the 1st and second. Budget units can only do the first.

UV Clarification - The Most Common Sterilizer on the Market
The first category of UV Sterilization is the main reason why UVs can such a bad rap in the industry. The vast majority of UV sterilizers available for sale will only be capable of clarification. In freshwater tanks and ponds, this is still a very good unit as it will eliminate green water, but don't expect it to do anything for bacterial and parasite mitigation or redox balance.

These sterilizers are usually hang-on or internal which makes them easy to install. These UV sterilizers offer little dwell time and comprise of many cheaper sterilizers on the market.

Sterilization - Mid-Level Units 
We start getting into more serious UV sterilizers at level 1 sterilization . These units are capable of actual sterilization with their higher dwell time. These units are most suited for common fish tank and pond usage. They have enough dwell time to not only clarify water, but can destroy harmful viruses and bacteria in your aquarium. Level 1 sterilizers are particularly useful in marine aquariums at helping to eliminating dinoflagellates.

Heavy Sterilization - The Best of the Best
This category represents the uv sterilizers with the best dwell time. They are the best of the best in the industry and common of what you will see in public aquariums. That is not to say that this is not available to the common hobbyist, it's just that sterilizers of this level are very expensive in comparison to others that do not have the dwell to be in this category.

These units are fully capable of water clarification, disease mitigation, redox balance, algae containment, and suitable for increasing the disease resistance of your fish population."

Regards,
Stu


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## fishboy75 (Jan 16, 2020)

Thanks for posting that Stu. I'm thinking about getting one. Need to do more research.


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## Idech (Nov 8, 2020)

@Stu W2 that's very interesting information ! Do you what level the Fluval unit is ? Did the article mention what products gave level 1, 2 and 3 ?


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## Auballagh (Jan 29, 2003)

Thanks 'Stu W2' for bringing that info in. 

The site provides a great read on UV Sterilization. And is actually kind of addictive... there is ALL kinds of good stuff to check out there!

https://aquariumstoredepot.com/blogs/ne ... sterilizer

And, there's no brand loyalty I can see.... just good reviews on all sorts of equipment available today.


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## Stu W2 (Nov 17, 2020)

Idech said:


> @Stu W2 that's very interesting information ! Do you what level the Fluval unit is ? Did the article mention what products gave level 1, 2 and 3 ?


Hello Idech,

From what I read on the box cover it's primarily a Level 1 Clarifier.

Regards,
Stu


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