I have a 200 gallon tank with 2 oscars and a peacock bass. There is 2 external canister filters (Rena Filstar XP2 & XP3) and 1 internal filter (All-Flo freedom). there is a sand substrate and there is a Rio 1700 pump.
Well flow/gph and bio filtration are 2 different ball games:
As said above if your parameters are good then ur bio is fine, but do you have enough flow or current in the tank? Are there a lot of dead spots, a lot of poo and left over food, if yes you need more gph combined with mechanical filtration. Bio keeps params good and has bb that converts waste to n03, mechanical simply traps debris and makes water clear.