I'm a Ex-veteran fish farmer in tanks, pond and pen aquaculture for 12 years. I gave up due to crazy up and down market prices and feed prices.
I'm only putting together a small 50 gallon for my son's turtle, goldfish, catfish and for nice looks.
From what I have seen for filters at the pet stores make me laugh since they are made cheep and seem so inadequate to filter good. So I'm going to use 2 - Watt's Big Blue whole house filters, one 20 micron pleated cartridge, and one empty refillable media cartridge so I can fill my own carbon and fiberfill. My biological will be the gravel in the tank with the flow from the filter coming up though the bottom of the tank though the gravel bed plate and though the gravel. Known as RUGF or reverse undergravel filter.
I will use bulkhead fittings to pipe externaly with large pipe and tubing and an large 950 gallon per hour pump.
Have any of you done the same?
I know some pet stores do it for they're tanks.
I haven't for fish farming because "looks" wasn't a consern, vast filtration was, so I had ugly huge filtering systems.