# How long should I run UV Sterilizer?



## evercl92

The green water is getting better, but I'm tired of dealing with it. I'm going to be purchasing a 18wt UV sterilizer for my 120gal tank. How long / often should I run it? Does it have to be on 24/7? Or can I run it 1 out of every three days or what?

TIA


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## FishFace

I would leave it on 27/7 until the water is clear. You should also do some large water changes to remove the dead algae.


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## houseofcards

You could run it as needed depending on your tank conditions. I have run one 24/7 on my 72g for well over a year and have not found any problems doing so.


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## Blacksunshine

for a planted only run it until you're GW issue has subsided. after that you can start your regime of ferts again.
yes a waterchange once things are clear will help. But will help more is getting to the root of your issue and find out why you got GW in the first place and fix it at the root.


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## jon_the_newb

I'd suggest running it 24/7 until the water clears, and then continue running it for atleast another week or two.

My 29G had a terrible GW problem. I cleared it with a diatom filter several times, the GW always came back. No surprise really, all the diatom filter was really doing was pulling the GW out of the water. The UV sterilizer will be doing a similar thing, killing it, instead of removing it though. This doesn't really address what caused the GW bloom in the first place. If you leave the UV sterilizer running, it will continue killing the GW as it tries to recover. All the while it's trying to come back, but getting killed off, it'll burn off whatever imbalance is allowing it to thrive. Thats my opinion anyway.

I somewhat tested that idea in my 10G. It had a GW outbreak, I tried a blackout first, 5 days, which only weakened the GW, it didn't get rid of it. I then tried the UV sterilizer for a couple days, enough time to kill the GW. It still came back. After it was back in full swing I put the UV sterilizer back on and left it for two weeks. A month later I had to tear down the tank, but at that time the GW had not returned. I also haven't had the UV sterilizer on the 29G in over 6 months.

Jon


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## evercl92

Blacksunshine said:


> But will help more is getting to the root of your issue and find out why you got GW in the first place and fix it at the root.


Yeh, I've went through that before. See here.

Never did get a definitive answer on that one.


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## AMP

I currently Got a 28W Aqua step on my 55, Put it in service a week ago, I have it on my Timer strip to come on with the lights and shut off when the lights go out.

I did not have the problem you were facing, but was irritated when I looked down the side of the tank and could see a slight tint in the water. So far it has seemed to keep things in check for me.

I have read articles stating you can run them 24/7 with no adverse effects, other state to only utilize when necessary. Currently I am well over stocked in my tank, and all my species seem perfectly content with what I am doing


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## yxberia

There is an experiment which shows UV oxidise trace element. Try googling will point you to the proper info. I would only on the UV for 8-10 hours AFTER photoperiod, to avoid additional warming.


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## Blacksunshine

evercl92 said:


> Yeh, I've went through that before. See here.
> 
> Never did get a definitive answer on that one.


Quite a read. only things I noticed there that differ from my own tank is your nitrate levels are a tad low at only 10ppm. I try and keep mine up around 20-30 because at 10ppm they get sucked up in no time. 
And as stated in the thread they mentioned your burst peirod may be a tad bit long. 
Myself I run 3.25 wpg all day and for only a 4hr peirod I up it to 6.5wpg. 
I'm also only pushing 2bps CO2. 
How do you have your CO2 introduced to the water? perhaps there can be some tweeking done there to make it more efficent. Adding pressurized was ultimatly what was the cure for my GW after having hit it with the UV. 
I honestly can't say what may be your issue otherwise. Is the tank getting direct sunlight?


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## evercl92

Blacksunshine said:


> How do you have your CO2 introduced to the water?
> 
> Is the tank getting direct sunlight?


CO2 is sent through a limewood airstone, which bubbles into my penguin 1140 powerhead, then sent across the tank:



No direct sunlight, although during the last couple hrs of the day, sunlight does light up that room. The tank is 20ft from that window, though.


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