[sde1500]

I wouldn't use that bath sponge. Some are treated with chemicals. And don't have to tell you what or if they are. I used some in my pod cultures and the cultures did very poorly. Use an aquarium filter sponge.

As for feeding phyto, I say go for it. I'm restarting my cultures after a brief hiatus. All the micro life in the tank and filter feeders will do very well with it. And if you keep dosing it the population will grow due to increased food source.