The number I put out of 5grams per hundred pounds is an average. That is why a safety factor is needed. Tilapia run in a range of 4 to 10 grams per 100#. I don't have specific numbers for other fish, but I'll see if I can find them. 5 is a conservative number for any other fish as their metabolism will be much lower. Metabolism is the key. Higher metabolism = more ammonia. Tilapia have a much higher metabolism than most other fish. Later I'll post some info on how to estimate ammonia production based on food intake.

Goldies have special issues as do tilapia. They make a lot of poop and that must be removed as well as the ammonia. The great thing about a growbed is that it is a great particulate filter. Using a flood & drain system with composting worms allows for the digestion of the solids.

The calculations are meant as a guideline, so test your water. The numbers will show that you don't need much of a bio-filter for ammonia. Nitrate, phosphate and solid removal is why you need large beds.