Phytoplanton

[Doug]

I fed my 170 about a capful/week. Always had nice sponge growth, but have some wierd ones now. :D

Except for that, I dont know how it effects the tank, good or bad. One must watch close for algae, {esp. red slime}, caused by excessive use.

I have read that clams like a feeding of it. As I dont have any, cant comment on that observation.

So, I would say, depending on your filtration and amount of filter feeders, be careful when using it.