It's like a closed formula
Protein Food + Nori = Import
Algae + Chaeto + wet skimmate + dry skimmate = Export
There's also
Evaporation Out + ATO in for water
Coral Skeleton "Out" and Ca+Alk+Mg in for mineral buid
Along with the various gas loops.
I'm going to weigh all my food and waste. In theory, Food > Waste for growth.
It's like any pet.. it eats and poops. In this case, the algae is part of the "out". The point is to use the food for energy and for material to build new tissue as the old wears out and needs to be replaced.
I think the Nori has better nutrient content than the algae. But the algae is fresh and full of pods... I really don't know.