filter feeding fish?

[wpbullock]

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

[jackalope]

Carp will eat algae, somewhat, but not a lot unless you cut back their feed ..... and they're edible ..... I'm not sure about Catfish, but I believe they are related to Mudsuckers and Bullhead, which, I think, are both good algae eaters. The trouble is, I'm not sure if/where you can get fry for Mudsuckers or Bullhead BTW, Carp can stand freezing water, as long as you bust a hole in the ice so they can get air ....... I was just planning to put an airstone in the tank for the winter to keep the air flowing in one spot so's it wouldn't freeze over.

[wolfracer]

I had a huge algae problem until I covered my tank to block sunlight, and put 50 channel catfish in it. Now there is 0 algae.

[jackalope]

I had a huge algae problem until I covered my tank to block sunlight, and put 50 channel catfish in it. Now there is 0 algae.

I thought cats would be good algae eaters

[badflash]

Green water and filamentous algae are two different problems, but both can be handled by blocking light. Cats are not filter feeders, so won't clear green water. If you have the conditions for green water, you probably don't have enough plants removing the nutrients.

Duckweed is a good control as it will blanket the surface, cut out the light, and absorb excess nutrients. You can remove the extra duckweed and compost it.

[wpbullock]

Thanks for all the replies.

Just as an FYI, I have chinese grass carp in my outdoor pond and it freezes solid every winter and they survive. It is spring fed, however, so maybe that provides some oxygen?.. As far as my fish tank, I plan to keep it circulating anyway and it is in a greenhouse so I doubt it will ever freeze, except maybe a skin of ice some very cold nights.

I think I may try to get at the nitrates with some floating lettuce. This link I found fascinating.

http://www.youtube.com/watch?v=FHBhyqowSEc

I was thinking of doing something like floating a large piece of styrofoam with holes in it for the lettuce. This will keep the algae down somewhat by blocking light and by sucking up nitrates..

The duckweed idea I like too but I worry that when I feed the fish, the food pellets will get stuck on the duckweed and not drop in for the fish to eat.

I still need to update my pictures to show my biofilter, blue gill and greenhouse!

Thanks,
Wes

[badflash]

If you have carp, you won't have duckweed. They eat it all. With a floating board you need to rig up a way to protect enough of the roots from the fish to keep them healthy. carp and tilapia both will eat them down to nothing if you don't.

[wpbullock]

bluegill shouldn't eat the roots, should they?

[badflash]

No, confirmed carnivores.