I have a terrible problem with green water.  I have had to do a 60% water 
change to get it to look almost normal, but within a week the water is green 
again.  Amonia is fine, temperature is fine.  I added 2 large banana plants 
in it hoping the plants would strive to keep the algae under control, but it 
keeps coming back.  This is a 55 gallon, temp between 72 and 74.  Only have 5 
fish in it (now since most die because of the green water).  I have a 
canister filter and biowheel on the outside and even run an undergravel 
filter system.  One side of the underground filter is airstone, the other 
side is a powerhead. I've added chemicals to clear it up also and it will 
help for a couple days at most, then back to green.  Even tried keeping the 
lights of a couple days. Any ideas anyone? Harv
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