Join Date: Oct 2007
Location: Ontario, Canada
Congratulations! You have green water!
Probably one or a combination of too much nutrients, lighting, or waste. It looks ugly, but it doesn't cause any significant harm to your fish.
New tank syndrome has to do with the nitrogen cycle, when nitro-converting bacteria hasn't caught up to the bioload in the water system yet. So I don't think it's new tank syndrome if there's no ammonia or nitrite spike, or high nitrate levels, or if your fish aren't dying.
I saw a thread where somebody neglected their tank and got super green water. He bought a UV sterilizer and that helped a lot. Best thing to do is probably water change, cut down on lighting and/or fertilizers, reduce the fishload and add more plants.