>>1300601>If you are growing it in the system for fish that eat plants
If I feed the fish with one of the plants being grown in the system, won't that eventually "wear out" the nutrients? There is a limited amount of nutrients within the system, and some of them must go to the plants, so if say I have 100 "nutrient units" in the first food given to the fish, 80 of them are absorbed by plants after being transported by poo, and I use 20% to feed the fish(meaning the plants I now use to feed them will equal 16 nutrient units), then the system will begin running on a deficit.
This leads me to think that the system inherently needs "outside food" every once in a while, with the first days being mandatory. Then it's not such a closed system anymore.
Of course it'll be easier if you have a larger farm and can get worms etc, but I still imagine that in a closed system where they are only fed certain foods, the outcome will be the fish waste will have limited nutrients, and will run on a deficit eventually