# UV Sterilizer on fresh water?



## daking (Mar 6, 2008)

just wanted opinions on whether or not I need one. I have been having small dots of green algae on my glass. I cant just rub it off, I need to use my handy dandy CAA card to scrape them off. I was reading about algae on plants and came across the description of green water, then to diatoms, then what they described as diatoms sticking to the glass and subsequently algae forming around these diatoms. It said a UV sterilizer creates a crystal clear water environment by doing something that I dont understand, but anywho.. I do have the same water colour issues as was described, I do regular changes, and parameters are in check.
is it worth the money? worth buying used? light replacement cost? what size (55 Gallon), can you "over sterilize?" as in the same idea as "too much water flow"?
This fish-keeping is getting waaay too involved!


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## Darkblade48 (Jan 28, 2008)

daking said:


> is it worth the money? worth buying used? light replacement cost? what size (55 Gallon), can you "over sterilize?" as in the same idea as "too much water flow"?
> This fish-keeping is getting waaay too involved!


Whether it is worth the money is up to the individual; personally, I don't see the need for one. The biggest function of a UV sterilizer (in my opinion) is to eliminate free floating algae (which causes green water), and even then, green water can be treated with less drastic (and less expensive) means, such as a temporary 3-4 day blackout.

Buying a UV light may be cheaper, but it also might be more expensive. You have to trust the seller when they tell you how many hours the UV bulb has been on for, as UV bulbs have a definite useful lifespan to them. Replacement bulbs aren't exactly cheap, as I am aware.

You can't really oversterilize; you can understerilize, though. You're looking for a balance between the rate of flow of water through the UV sterilizer (i.e. if it is too fast, the UV rays won't have time to kill the bugs/algae, but if it's too slow, you might not be able to get the desired kill ratio that you desire).


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## daking (Mar 6, 2008)

I do have the green water, I think, because if I leave the lights off I can't see anything and it appears really clear, then after the 14 or so hours of off time, the water is clear. However after about 4 hours of the loights being on, the water gets greenish yellow and not clear.its rather annoying since I know all is finally working on the tank, now this!


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## Darkblade48 (Jan 28, 2008)

Yup, sounds like a mild case of green water (and really, I mean mild; full blown green water is when it looks like pea soup, and you can't see anything past 1-2 inches into the tank). 

You can try something a little less drastic than a UV sterilizer first (i.e. a blackout). Green water is usually caused by a small amount of NH3/NH4+ that was introduced into the aquarium (i.e. stirring up too much substrate during a water change would do it).


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