"I don't know about the filter part, but I know plants LOVE fish poop! You may already know that and are just asking about the filter part, if so, sorry :)"
"I'm harvesting corn (a tad late, I think), have spaghetti squash, tomatoes, pole beans, pumpkins and cotton growing. Just ordered sunflowers and more corn from Native Seed Search to try to regional varieties."
We have a small little fish tank, about 2 1/2 gallons, but our goldfish is prolific pooper. S/he goes through about a filter a week. I'm wondering, is the carbon filter and fish waste, less plastic frame for the filter, of course, compostable?