The article suggests that the difference is the water recirculation - that the "waste" water is cleaned rather than being removed. Is that how your farm's raceway worked?
Yes, it was cycled back through and filtered (through sand and plastic I believe) before being re-pumped back into the system from a retaining pond, then supplemented by a ground water pump to account for evaporation or other loss. Oxygen was pumped in separately from liquid oxygen tanks.
Disclaimer in case there are any more questions... this is about as far as my knowledge goes on this. lol I'm sure it was much more complicated than what I understand.
