Green water

[dirtydogg]

long story so bear with me. . .
My cousin moved about 2 months ago and when he did he bought a new canister filter for his 55G tank. He didn't try to colonize the new filter with bacteria, just ran it after draining and cleaning the tank. Now his water is green. Really green! So green that I couldn't even see his 11 inch tiger oscar in the tank unless he was facing the glass. I went over there when he called me in desperation and tested his water, and as expected once he explained this to me his tank is going through it's cycle again. From the readings I got it's almost finished.
Ammonia: 0.00ppm
Nitrite: 0.30ppm
I've convinced him to get rid of at least one of his fish maybe two, as he is overstocked with 2 oscars(a 11 inch tiger & an 8 inch white tiger with a busted lip) a common pleco(about 11 inches long from what I could tell) and some overgrown feeder fish in the tank. What else can I tell him.
I'm going over there tommorow to take his nitrite reading again. I want to help him as it was this same tank when we roomed together that inspired me to get into the hobby. Any suggestions?

 

[itZme]

It's probably getting some sunlight (either directly or indirectly). Try doing a search of "green water" for solutions. Or try searching "blackout method" or "black out method".
I resorted to a chemical in my battle against green water. I posted pics >here<. I know there are some drawbacks to using a chemical for this but I found it to be a good solution in my case.

Good Luck!

-- itZme

 

[Purplesmurf]

Your best bet is going to be a blackout for three days. Perform a 50% PWC and then cut poster board to fit over all surfaces that will allow light in, tape them on, and turn off the lights. Perform 50% changes each day during the black out. After you have turned the lights on again do 25% changes each day until your cycle has stoped and the water is clear.

I do not know if it will be necessecary to stop feeding the fish during this period but it wouldn't hurt anything. Turn any CO2 injection off aswell, plants don't use it in the absence of light so you'll slowly suffocate any fish in the tank.

Green water is often an indicator of old tank syndrome. Basiclly OTS means your friend hasn't done any water changes in months, so all the food, chemicals, fish wastes, etc. have been sitting in the water and are now feeding mono-cellular life -- algae.

Good luck.