You need to evaluate oxygen ...

You need to evaluate oxygen transfer rates on your stream and in the AB.  If this is a new build all of the manufacturers have software that will allow you manipulate different schemes to find the most efficient.  You will normally use fine/medium size diffusers for the microbubble creation, but will augment the mixing, if complete mix AS is your layout.  My suggestion is to be forward thinking for expansion and redundancy.  Back up blowers and a bulk tank of hydrogen peroxide (for upset conditions lowering DO) are in my opinion essential safeguards that prevent violations.  You lose about 1% active H2O2 a year in the proper tank protects from UV.  Cheap way to augment an overloaded system.  Thanks, Sean