# UV & green water Question



## mommyeireanne (Oct 24, 2007)

Well I have had the UV in for 4 or 5 days now and my water is still green. It's only 10 gallons, and the 5w Submariner is rated for up to 40 gal. I have it turned to high as the book suggested, but I still have greenish water. Will it clear on it's own, or do I need to make water changes? I have my lights on for 8 hrs a day, split, but could lower it more, as I just did a big trim and changed 1/3 of the water when I put the UV in. I guess I'm concerned about the light as Drs Foster & Smith send me a used Submariner. I think I'll be contacting them regarding a new bulb or partial refund. I was ambivalent since it seemed to work. I figured it would take some time, but I am worried about my bulb not working.

*For those who used UV to clear green water: How long did it take, and did you also make water changes? *

It's not cloudy or peasoupish. Just tinted green. Everybody in there is happy, and I just took out my amonia alarm because I've never seen an amonia spike. Testing is infrequent now, but I always get the same: no nitrite, no nitrate, very hard (300 ppm) & very alkaline (7.8 pH) water. Temp is up to 80 deg F now with the new UV, bit warmer than I wanted but all shrimp and snails seem ok.

All advice on green water in El Natural appreciated.


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## mistergreen (Mar 3, 2007)

Green water is harmless to fish and such... Just do a 50% water change and keep the UV running.. I always thought to keep the UV running as low as possible.. The longer the diatoms are exposed to UV, the better it'd get killed.

And leave the lights off while doing this.


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## Diana K (Dec 20, 2007)

You might run the UV slower, so the green algae is exposed to the light longer. Run the pump at the slowest recommended rate, not the fastest. 
Do water changes. When the algae dies there could be a rather large spike in ammonia as it starts to rot.


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## BryceM (Nov 6, 2005)

The UV unit will kill the waterborne algae but will not physically remove it from the water column. Once it's dead, you can easily get rid of it with a few waterchanges, fine filtration (diatom filters work great), or you can just wait it out. The dead algae cells will eventually fall apart and their contents will gradually settle out in the tank, but a few WC's will make things go much faster.

I don't agree that it's necessary to turn off the lights. UV is VERY effective at killing GW algae (assuming your UV bulb isn't 2 years old!). Turning off lights will only makes things harder for your plants.


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## mommyeireanne (Oct 24, 2007)

Thanks. I've been looking forward to not having to change the water much. One more small hurdle...


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## wiste (Feb 10, 2006)

> For those who used UV to clear green water: How long did it take, and did you also make water changes?


In the past with a new setup I used a UV sterilizer to attempt to correct green water.








After running the sterilizer for two days the water was no longer green.








As can be seen the UV sterilizer did not help water clarity.

If water clarity is a concern, then a polishing filter, such as a diatom filter or a micron filter is a great thing to have and use. Using Seachem purigen is also a really good way to get a polished look to the water.

Tinted water may not be the same thing as the green water seen in the pictures above.
Usually, green water is preceded by a cloudiness and then a transformation into the pea soup.

If the tinted water did not clear or turn white after 4 days with a UV sterilizer, then polishing the water would seem to be the way to go. A large water change may be just as effective in restoring clarity. Even when polishing, a large water change will significantly reduce the time to restoring clarity.

A more natural approach would be to leave it alone and let it clear on its own. You did not mention how long the tank has been setup. If the tank is newly setup, then I would leave it alone for the first six weeks to allow the tank to stabilize unless the condition worsens.


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## mommyeireanne (Oct 24, 2007)

It's 4 months old and I think I have single-cell algae.


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## wiste (Feb 10, 2006)

> It's 4 months old and I think I have single-cell algae.


Using a 9W on a 75 gallon with a 30 gallon sump produced the results above without a water change.


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## Homer_Simpson (Apr 2, 2007)

Barley straw has been successfully used in ponds to prevent and eliminate green water. Don't know if it work in an aquarium, but you could try. It may take a while to see the results. Just put some in a pantyhose or filter bag and suspend it in the water(clip it to the tank) where it receives the most light and oxygen from agitation. I use it in my 10 gallon tank with a UV sterilizer, no conflict. I never had green water since setting up the tank on July 22 2007, but cannot say if this was due to the UV sterilizer or barley straw, plus the tank is a high tech non-natural planted tank, but barley straw is a natural solution to green water. 
http://www.pondsplus.com/Infofiles/art03.htm


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