I have a lot of "green water" in my tank due to nitrates fertilizing algae growth. I think Tilapia would eat this and clear the water up somewhat but I don't want to heat my tank in the winter (it is in my Ohio greenhouse). Will the chinese grass carp filter feed and keep the tank somewhat clean? Any other fish you all know of that can withstand 32 F water in the winter but provide some cleaning action in the tank and it's water? If I can eat them in the end, that would be ok too!

What about non-fish that will co-habit with my blue gill and keep things a bit cleaner but the bluegills won't eat?

THanks,
Wes