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UV Sterilizer and Green Water: How long?

30491 Views 8 Replies 7 Participants Last post by  hoppycalif
How long does it take for an UV sterilizer to clear a case of green water? I've hooked a JBJ 9W unit on my 29G tank for 2 days and it's still as green as it was when I first hooked it up. This is my first time using one.
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I reciently used a UV for greenwater also. The gw had been in full bloom for over a week once I wa able to borrow the UV from a friend. After 2 days the water was crystal clear. I ran a Hagen Quickfilter at the same time, figuring it woul dhelp remove some of the greenwater and that it would remove the dead greenwater. In total I ran the UV for 3 days, just to be sure. As I said though, I did not have a full on bloom any more so logically it would seem to me that it woudl take 4-5 days to fully clear up a major bloom.

What type of UV do you have and how is it hooked up? Is there any indicator that the UV bulb is working?
It took four or five days for the green water to clear up in my experience. After a few days the color changes to a more greyish green, and it takes a few more days for the water to get clear. I assume that the algae gets killed, but stays suspended for a few days longer.
I just went through this. I hooked up a 9w coralife turbotwist to my 72g and for the first few days I didn't notice much by the 3 day it looked alittle clear and within a week it was clear. Now it's so clear it doesn' look like there is water. I've kept it running 24/7, but might convert to a lights on/lights off.

Dennis mentioned some good points, make sure the bulb is working (there should be a way to tell). Also the flow rate of your filter will affect the exposure time so that can also have an affect on how fast it clears.
Oh, all this time I was thinking the effect was within 24 hours. :oops: I've just done a water change to help the UV sterilizer work faster.

I have the JEBO 9W model. I wish I had purchased the Coralife model. The bulb does work. They should make it easier to check than to dismantle the contraption.

Thanks everyone.
With the Jebo model, you can see the light coming from throughout the outlets of the unit. My question is how did you hook yours up. A pic would be helpful. I just floated mine in the tank for 3 days. It worked well but was unsightly. I want a more permanent location like on the back of the tank so I can hook it up as need be fast.
One of the worst problems I have had with my unit is using the stiff, vinyl plastic tubing. It was too stiff to be useable. I ordered red colored rubber tubing that was more flexible, but I would like to have the even more flexible silicon tubing, even though it is more expensive in larger sizes.
This is what I did to install a UV algae killer into my father's pond. The inlet and outlet on the filter itself came with hose barbs on the threaded nipples. I threw those away. Went to the Home Depot and picked up some reduction fittings (the original pipe was 2" and I reduced it to 1" so as to fit the 1" threads on the filter), some blue submersible glue and pvc cleaner, and a 3 foot length of 1" pvc with a few elbows. Glued em' up and put the contraption in the water and it runs like a champ even with the reduction for the UV filter. I am hearing it takes about a week to get the green gone. I will try to remember to repost in about a week with an update. :idea:


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A three to four day total blackout of the tank will also eliminate the green water, and, like the UV filter, if you can't figure out why you had green water and correct it, the elimination is only temporary. Unfortunately I rarely am at all sure why I get green water, so I make numerous changes, hoping one of them eliminates the problem.
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