No such thing as too much biological filtration. The bacteria will grow to whatever level is necessary to process the waste (ammonia) in your tank. Once the bacteria population has reached the right level, it will stop growing due to limited food source.
There is such a thing as too much mechanical filtration if it creates too much current in your tank, but that should be pretty obvious.
92-gallon corner tank, 100lbs of LR
, 140lbs of sand, 250watt 10,000K MH
, 110watts of actinic PCs, Mag 7 return, custom refugium, AquaC EV180 w/ Mag 5
Female lyretail anthias, eyelash blenny, tomato clown, saddleback clown, firefish goby, 2 sand-sifting stars