I've been searching for over an hour and can't find the max flow rate for a 55 gallon bio filter. I thought I read there was a max gph somewhere but search doesn't seem to find it.

My situation will be a 3500 gallon pond -> 4" BD -> 4" pipe -> 330 gallon SC -> 3" pipe -> 55 gallon bio -> ?" pipe -> ? pump -> ?" pipe -> 3 TPR's.

Any help on the ? for pipe size would also be a plus.