# UV Sterilizer and cycling



## jasa73 (Jun 3, 2007)

I dont think it would mess it up necessarily but i think it will cut down or impede colonization. The question is, are the bacteria all lose and free floating in the water? Its only the bacteria in the water that passes through the UV light that will be killed. Any bacteria adhering to substrate, plants, filter media will be fine. But anything free flowing will have a chance to pass through the UV and be killed. 

My question is, why are you setting one up when cycling? Are you concerned about algae?


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## Blackheart (Jul 5, 2011)

Yeah I usually have algae issues when setting up a tank, it's no big deal I know, but I was thinking about purchasing one anyways to keep the tank in balance, so I figured why not.


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## houseofcards (Mar 21, 2009)

I've setup tanks with and without a UV. No noticeable impact on cycling and/or plant growth. Remember the biomedia and substrate house most of the biofilter and of course they don't pass thru the UV. If a UV messes up the cycle so would every major water change. Not that it's always needed but the UV is win-win. It will prevent GW and if the flow is slow enough parasites as well.


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## micheljq (Oct 24, 2012)

UV will only kill green water. It will not stop other algae though.

Michel.


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## Blackheart (Jul 5, 2011)

According to whom? I've read different things online that a UV sterilizer rid lots of people of algae.


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## micheljq (Oct 24, 2012)

UV will kill algae in water column, the water pass in the UV sterilizer and algae there will be killed. However algae spores on rocks, plants, glasses, etc. will not be killed. Most algae can develop and spread from there, without ever going in the water column.

Michel.


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## All4Fish (Jun 23, 2014)

If I have UV will it help replace quarantine tank as I am short on space?


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## CrypticLifeStyle (Jan 16, 2013)

I always found this guy's page to be helpful on explaining it all. 

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


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## Diana (Jan 14, 2010)

Do not skimp on quarantine. 
If you are short on space set up the quarantine tank as a temporary tank for about a month. When the livestock is moved to the main tank take down the Q-tank. 

I use a UV sterilizer on the Q-tank only if I can see the fish have a problem. As an example, Ich. Used properly, UV can stop Ich from reproducing, so it never gets beyond the initial discovery.


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## exv152 (Jun 8, 2009)

UV will kill any type of algae spore that flows through its light, whether it be green water spores or other, it's just more useful for green water spores because green water spores are exclusively free floating. UV won’t harm your beneficial bacteria in a cycle as BB only colonizes on surfaces and not in the water column.


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## klibs (May 1, 2014)

Don't skimp on quarantine. I made this mistake and lost about half my stock to ICH. I will now be quarantining any fish I get from now on....


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## Fissure (Jun 29, 2014)

Depends on the flow as well, to high flow through the UV filter and it pretty much does nothing at all.


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