That's like trying to live on bread crumbs. It's impossible. My goldies get brine shrimp, peas, lettuce, flakes, floating pellets, and sinking granuales. And usually, atleast one of them is pooping .
if ya want something that eats the suspended algae, you could get some filter feeders like freshwater mussles, they filter something like 60 litres each per day (but if they spawn their larvae are parasitic so not the best for your fish...)