# UV Light Effect on Nitrifying Bacteria?



## genocdex (Jul 16, 2012)

the only thing i can think of using the uv in fw tanks would be to help rid the tank of green water and or some water born viruses. besides that i think its useless. the bb stay mainly in the filter and on the substrate. barely any (if any) are in the water column, thus untouched by the uv light. if you installed a uv light directly over a tank then thats a different story.

what are you trying to accomplish using the uv? cleaner water meaning what?


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## etane (May 14, 2012)

Thank you for your reply.

The UV light I am looking at is an inline. So, it will be plugged in after my canister filter. So, it seems the nitrifying baceteria will be perfectly safe with this set up according to what you said.

What I am trying to accomplish is to minimize possible air pollutant the tank might contribute due to growth of unwanted algae and other type of bacteria in the water. The side affects would be I wouldn't have to scrape algae off my glass as often and perhaps the fish will be healthier?


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## genocdex (Jul 16, 2012)

i wouldnt count on it. if uv really helped prevent algae then every one would have one. keeping your parameters in check (light, nutrients, co2, stock, filters ect) you will be able to prevent all forms of algae. 

as for healthier water for your fish, live plants would help but you should realize that the uv light is not a filter at all it just kills off viruses and or bacteria in the water.


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## etane (May 14, 2012)

Disagreement on semantics? I know nothing will "prevent" algae but isn't UV used to "reduce" algae?

And, I know UV is not a filter but water is funneled through a tube that allows it to be exposed to UV rays from a bulb. So, I know the UV is not in of itself cleaning the water. 

Rather, am hoping it can prevent pollutants from colonizing in my tank water which I think, in my case, UV will be both safe and useful for me to use?


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## steven p (Jun 22, 2012)

Uv will not reduce algae on the walls... Common misconception..

Also, it will not help with any sort of air pollution like aerosol and/or cigarettes.


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## etane (May 14, 2012)

steven p said:


> Uv will not reduce algae on the walls... Common misconception..
> 
> Also, it will not help with any sort of air pollution like aerosol and/or cigarettes.


Ah, thanks regarding the algae on glass comment. 

Regarding the air pollutant, didn't mean that an inline UV filter will reduce aerosol or smog. Rather, I meant I didn't want the tank to spread germs and bacteria into the air as I am afraid little kids that are in the same room as the aquarium is in might experience or develop allergic reactions.


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## genocdex (Jul 16, 2012)

i didnt know fish could spread things to kids that they could be allergic to. the only thing i can think of that fish can transmit to people and vice versa would be TB and maybe a worm or something.


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## etane (May 14, 2012)

genocdex said:


> i didnt know fish could spread things to kids that they could be allergic to. the only thing i can think of that fish can transmit to people and vice versa would be TB and maybe a worm or something.


It's not specifically the fish that's transmitting things to kids. I am afraid if water quality goes south, it might create bacterial pollutants that can cause allergic reactions.


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## OVT (Nov 29, 2011)

genocdex said:


> i wouldnt count on it.


genocdex pretty much summed it up. UV is a very specialized tool for very infrequent jobs. But to answer your question, no it will not hurt horrifying bacteria. Imo, your money are better spent on something more useful.

via Droid DNA Tapatalk 2


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## fearsome (Feb 16, 2013)

UV is mutagenic to DNA, this is the process by which it kills bacteria. The thing is bacteria, especially cyanobacteria and other photosynthetic organisms are going to typically be used to dealing with UV to some degree. Assuming you have a powerful UV light very close you will be doing some killing of everything that passes through it. 

So what this likely means is that the algea that sticks to the wall will just have more to eat and it might very well increase the problems on your glass. Anything that is floating free in the tank is more likely to pass by the light and be killed.

Even so it would be interesting to hear your results if you try it.


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## EricSilver (Feb 23, 2004)

Yes its safe, it will only kill nitrifying bacteria in the water column. 

I have a Current Gamma 15W that runs 24/7 -- and I am adding a second, identical one tonight -- because my tank has bright lights and gets hit with direct sunlight each afternoon. If I switched the UV off I would have green water in less than 48 hours. Now I have none, nor any on glass, rocks, etc. 

There is more to it than just direct sterilization. Google "UV redox potential" and study what you find. 




etane said:


> Just curious whether it's safe to use UV light in a freshwater aquarium as the UV light might or might not kill nitrifying bacteria?
> 
> There's some inexpensive UV lights made by Aquatop that I might like to try if it's safe to use.
> 
> ...


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## Steve001 (Feb 26, 2011)

etane said:


> Just curious whether it's safe to use UV light in a freshwater aquarium as the UV light might or might not kill nitrifying bacteria?
> 
> There's some inexpensive UV lights made by Aquatop that I might like to try if it's safe to use.
> 
> ...


There's absolutely no good reason to use UV light unless something is wrong with your tank. Keep the water clean by changing the water and limiting livestock. In close to 30 years of keeping one planted tank I've only had to use a UV sterilizer once.


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## EricSilver (Feb 23, 2004)

Steve001 said:


> There's absolutely no good reason to use UV light unless something is wrong with your tank. Keep the water clean by changing the water and limiting livestock. In close to 30 years of keeping one planted tank I've only had to use a UV sterilizer once.


Congratulations. 

Understand,however, that your circumstances are not the same as those of others.


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## houseofcards (Mar 21, 2009)

Steve001 said:


> There's absolutely no good reason to use UV light unless something is wrong with your tank. Keep the water clean by changing the water and limiting livestock. In close to 30 years of keeping one planted tank I've only had to use a UV sterilizer once.


I would disagree. 

For fish reasons alone their are many reasons to use a UV. Acclimating is much easier when fish are stressed since their immune system is compromised and the water is clear of many disease causing parasites. I have obtained much higher acclimation success for difficult fish like Cardinals when using a UV not to mention fish that are less likely to get sick. 

If balancing a tank is by turning down lights or adding plants not everyone wants to do that. Balancing a tank can many times, be a compromise to what you really want the tank to look like. A UV will give you more wiggle room if your bio filter isn't up to task. Plant wise I've never noticed a downside to using a UV and if your bottom get's stirred up and you release nutrients into the water column your covered there as well.


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## gSTiTcH (Feb 21, 2013)

Incidentally, you don't get pollution/germs from algae in the water. You'll get oxygen. Algae is not a health risk, it's an aesthetic issue. Did you know that the majority of the oxygen we breathe comes not from trees, but from algae? You might create some odors from really bad water quality, but not allergic reactions or infections. You're far more likely to cause a mold growth from owning the aquarium. I get the distinct feeling this tank is in an office or something. Am I correct?

The UV sterilizer is a hotly debated topic, but most people don't really cite any science to back claims. I will tell you my experience and let you decide:

I do run a UV sterilizer from time to time.
1) If I notice illness in my tank;
2) If I have free-floating green water algae;
3) Periodically for about a week as a routine maintenance item;

I have not seen any negative effects on my fish or water parameters. They are kind of expensive, but will clear up green water. I don't let glass borne algae build up long before I do a manual removal.

UV is not the end all solution to tank problems. If you elect to use it, it's harmless. Nitrifying bacteria in the water column will die. However, they are a very minor contributor to your biological filter and are easily replaced.


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## Steve001 (Feb 26, 2011)

EricSilver said:


> Congratulations.
> 
> Understand,however, that your circumstances are not the same as those of others.





houseofcards said:


> I would disagree.
> 
> For fish reasons alone their are many reasons to use a UV. Acclimating is much easier when fish are stressed since their immune system is compromised and the water is clear of many disease causing parasites. I have obtained much higher acclimation success for difficult fish like Cardinals when using a UV not to mention fish that are less likely to get sick.
> 
> If balancing a tank is by turning down lights or adding plants not everyone wants to do that. Balancing a tank can many times, be a compromise to what you really want the tank to look like. A UV will give you more wiggle room if your bio filter isn't up to task. Plant wise I've never noticed a downside to using a UV and if your bottom get's stirred up and you release nutrients into the water column your covered there as well.


Neither of you understood me. Unless there's something wrong there's no reason to use a UV sterilizer on a daily basis.


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## EricSilver (Feb 23, 2004)

Steve001 said:


> Neither of you understood me. Unless there's something wrong there's no reason to use a UV sterilizer on a daily basis.



Something is very wrong with mine: Every afternoon, the sun lights up my tank like a flare. 
:smile::smile: So I have no choice.


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## EricSilver (Feb 23, 2004)

houseofcards said:


> For fish reasons alone their are many reasons to use a UV.


Another big motivator for me. 

In the past, my fish have inevitably picked up some form of parasite -- my fault for feeding live worms -- but some were not food-borne, and if I can fight them with UV, I will.


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## CrypticLifeStyle (Jan 16, 2013)

I bought my first UV back in 1998, and honestly it was one of the best investments i think i could spend my money on prolonging the health of not only the fish, but maintaining a superior water quality. I now run 2, with 1 that rotates on a schedule on my tanks. 

Water is always super clear, never any algae in the water column, destroys any fungal or bacterial issues i may had or could have due to the amount of trading i do. 

Probably a waste of time for planted tanks unless you have water algae, but for fish keepers its a nice "weapon" to have, or have for people that do a lot of trading or can be used in qt tanks as it can kill ich too in the water column. I've never heard a person that bought one, and use's one ever say they regret it.

Here's a good article for the science behind it for those that wish to have to part to read  I think most of the misconception i do see though is proper flow rates for them. 

http://www.americanaquariumproducts.com/AquariumUVSterilization.html


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## houseofcards (Mar 21, 2009)

Steve001 said:


> Neither of you understood me. Unless there's something wrong there's no reason to use a UV sterilizer on a daily basis.


I think I did understand. What I'm trying to say is on the fish side it's preventive. It's not that you definitely need it, but they will prevent fish issues and acclimation is definitely easier. You mean to say in all the years you've been doing this you never lost a fish from illness during acclimation or otherwise. It might have been prevented by a UV.

On the tank/plant side, many tanks are forced to add more plants, etc to create more uptake. There isn't necessarily anything wrong with those tanks, but you do tend to compromise more to create a larger bio filter.

In addition as mentioned water is definitely clearer in most setups with a UV.


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## MrSlumpy (Jan 4, 2013)

I'm currently running an inline UV sterilizer on a secondary canister filter. My tank gets hit with about an hour of direct sunlight every day (no other option for placement in my house.) I didn't install it with the expectation that it would solve any algae problems. I just thought it would be a good addition to my regular regime, and I also figured it would help when adding new (possibly sick) fish. Those that are so opposed to the idea seem to be of the opinion that it is not necessary. My thinking is more like *It's cheap and it certainly can't make anything worse!*


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## etane (May 14, 2012)

Since I started this thread, I've ordered and received the Aquatop 5W inline UV filter. My tank is still empty, so it will be awhile before I get to use it.

As many of you have already pointed out that many of you already use UV for preventative purposes. And, that's exactly my reason for getting this. 

True, I think it's 80% of the earth's oxygen is produced by marine algae as one of you pointed out, but I just don't know what other type of air borne bacteria would be emitted from the tank if and when my cleaning habit is neglected.

The tank is in my office as one of you assumed correctly. However, I am in the process of converting the office into a nursery, and I don't have another room for the tank where there is less sun exposure. The tank is staying in this room for now.

So, that's why I am being a bit more careful about what bacteria might emit from the tank. 

But, having the tank treated by UV could mean I might have less fish and shrimp deaths as well. So, I see a lot of positives in using an UV. The only negative I was worried about is whether nitrifying bacteria would be killed.

But, since the bacteria mostly live in the canister and in substrate, I guess I wouldn't have to worry about that since the UV I got is inline, so it won't expose nitrifying bacteria to UV rays.

Thanks all!


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## Steve001 (Feb 26, 2011)

EricSilver said:


> Something is very wrong with mine: Every afternoon, the sun lights up my tank like a flare.
> :smile::smile: So I have no choice.


My tank receives direct sunlight yet I don't need to run a UV light.


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## Steve001 (Feb 26, 2011)

houseofcards said:


> I think I did understand. What I'm trying to say is on the fish side it's preventive. It's not that you definitely need it, but they will prevent fish issues and acclimation is definitely easier. You mean to say in all the years you've been doing this you never lost a fish from illness during acclimation or otherwise. It might have been prevented by a UV.


Acclimating fish isn't what the op was asking. They were asking if an UV sterilizer should be used as a prophylactic on a continuous basis. And the answer is still; it's not necessary. 

Never any diseases. Fish settle down quite quickly when introduced to a tank that's heavily planted because they have many hiding places to relax to. And if memory serves some plants produce and release anti bacterial chemicals into the water, like duckweed for example.




houseofcards said:


> On the tank/plant side, many tanks are forced to add more plants, etc to create more uptake. There isn't necessarily anything wrong with those tanks, but you do tend to compromise more to create a larger bio filter.


I read the book called The Optimum Aquarium decades ago and one of the principles stated in that book is to plant heavily from the start. That is a principle that has not changed. I don't understand the rest of what you said or what it has to do what the op's question so I won't comment.



houseofcards said:


> In addition as mentioned water is definitely clearer in most setups with a UV.


That may be a subjective evaluation.

I've never had any diseases. That could be do to the store which took great care in quarantining and medicating their fish before sale. The only time I had to use a uv sterilizer was to clear up an outbreak of green water.


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## UDGags (Sep 13, 2009)

I pretty much only use my UV light after major rescapes/trims, if I have a disease and when I get new fish in (in case they bring something with them). It's more out of being safe but I suspect I could get away without it.


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## houseofcards (Mar 21, 2009)

Steve001 said:


> Acclimating fish isn't what the op was asking. They were asking if an UV sterilizer should be used as a prophylactic on a continuous basis. And the answer is still; it's not necessary.


So we should hide a benefit, simply because the OP didn't ask it in their initial question? I'm pretty sure most of us have fish with our plants. 



Steve001 said:


> Never any diseases. Fish settle down quite quickly when introduced to a tank that's heavily planted because they have many hiding places to relax to. *And if memory serves some plants produce and release anti bacterial chemicals into the water, like duckweed for example*.


So in 30 years of fishkeeping, you never lost a fish to any disease? You never lost a fish during acclimation? 



Steve001 said:


> I read the book called The Optimum Aquarium decades ago and one of the principles stated in that book is to plant heavily from the start. That is a principle that has not changed. I don't understand the rest of what you said or what it has to do what the op's question so I won't comment.


If your aquascaping, you might not want to stuff the tank full of plants, your going for a certain look. Having to stuff the tank full of plants is a compromise in how I want things to be setup. Even with a heavy plant load a UV is still more reliable to clear GW, ec.


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## Steve001 (Feb 26, 2011)

houseofcards said:


> So we should hide a benefit, simply because the OP didn't ask it in their initial question? I'm pretty sure most of us have fish with our plants.
> 
> 
> 
> ...


Look I've made myself clearly understood, but it seems some people still don't understand. If your tank is functioning without any problems, ANY PROBLEMS, -capice?-, it's not necessary to run an UV sterilizer as a daily prophylactic. You do understand in this context what is meant by prophylactic?
Geez whiz, you can't read. I said in an up post that I did use a UV sterilizer once to clear green water because there was a problem. So, do you understand now what I'm saying?


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## houseofcards (Mar 21, 2009)

Steve001 said:


> Look I've made myself clearly understood, but it seems some people still don't understand. If your tank is functioning without any problems, ANY PROBLEMS, -capice?-, it's not necessary to run an UV sterilizer as a daily prophylactic. You do understand in this context what is meant by prophylactic?
> *Geez whiz, you can't read.* I said in an up post that I did use a UV sterilizer once to clear green water because there was a problem. So, do you understand now what I'm saying?


I think the difference here is really preventive vs reactive. If you prevent something you wouldn't know what would happen. If a fish gets sick without a UV one's treatment is reactive. If your fish doesn't get sick it's preventive. If you stir up the bottom and you get GW it's reactive to treat it, if you never get GW it's preventive. So in those examples, there might not be anything wrong with your tank but there are benefits to using a UV. Not all tanks have the same plant mass so your mileage will vary with plants helping out, a UV will work in all tanks. 

On water clarity. If you have a piece of white paper on a desk and grab another piece of white paper you might realize the first piece is off-white. So the UV will give you the 'whitest' paper out there. 

No reason to get personal with comments like "Gee Whiz you can't read" if one has a different perspective.


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## Steve001 (Feb 26, 2011)

houseofcards said:


> I think the difference here is really preventive vs reactive. If you prevent something you wouldn't know what would happen. If a fish gets sick without a UV one's treatment is reactive. If your fish doesn't get sick it's preventive. If you stir up the bottom and you get GW it's reactive to treat it, if you never get GW it's preventive. So in those examples, there might not be anything wrong with your tank but there are benefits to using a UV. Not all tanks have the same plant mass so your mileage will vary with plants helping out, a UV will work in all tanks.
> 
> On water clarity. If you have a piece of white paper on a desk and grab another piece of white paper you might realize the first piece is off-white. So the UV will give you the 'whitest' paper out there.
> 
> No reason to get personal with comments like "Gee Whiz you can't read" if one has a different perspective.


I give up. You win.
P.S. That wasn't personal. It is a statement of fact that I used it once on green water because green water is a problem.


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