I think the key is that the inhabitants need some amount of phosphorous but the $64K question is "œWhat is the minimum (or optimal) requirement?" Assuming that what is not consumed and used would be excremented into the tank. While we are all guessing based on each individual tank and its mix of inhabitants, it's shocking to see how high the percentage above sea water is for some of the foods.
phosphorous is a direct link to nutrition. That why you see more in pellets and flake foods.... they are packed with nutrition, there designed that way. The down side is the with that nutrition come phosphorous. It really a delicate balance. I prefer to feed more frozon foods for that reason, also keeping angels I'm able to feed more and more often.... "keeping them form nipping as much".