Large Scale Greenwater Options

[goldfish321]

I have succesfully made greenwater before and understand how important aeration is but, what is the minimum aeration per liter for greewater? Or does it depend on how many fish there are?
I am thinking of starting greenwater in outdoor tubs that are around 100 gallons each but dont know if just one air stone will be enough. I think it should be because our goldfish are only harmed when oxygen is supersaturated. If the supersatured oxygen is then being aerated with 20% oxgen (in the atmosphere oxygen is only at about 20%) shouldn't it balance out even if the stone is unproportional to the amount of water.
Hoping for some expert advise!