Experimenting with filtration has been one of my favorite parts of fishkeeping for many years. I've always built filters even back in the day when undergravel filters were all the rage. I've still tossed around putting built-in UGFs in my smaller tanks, but that's a topic for another post.
The barrels will be fed from a 3" pipe connected to a bulkhead in the lower part of the tank. I may have them all on one side connected to one, but have considered connecting 2 to 2 different 3" bulkheads.
1.5"-2" pvc will send the water from the 3" pipe to the bottom of the barrel and into whatever media I have in it. As I've said, it could be chemical like activated carbon, biological (i have tons of bioballs or could order scrubbies from zennzo), or a combination of both. I could even stuff them with floss and make them mechanical filters. Just about anything you would put in your Eheim or Fluval could go in any of these barrels.
Water will flow through a smaller pipe fitting with a trap to prevent media escape to 1000 gph pumps positioned right at the water level, so pretty much no head pressure on them. The forced flow from the closed loop keeps the plumbing flooded and allows air to escape.
Two possibilities happen at the return after the pump.
Return directly to tank with the venturi thing (forget name of it) that increases water flow for circulation.
or
Return to the equivalent of Aquaclear 11000 filter chambers for even more polishing.
That's just one part of the filtration. I'm borrowing ideas from aquaponics and waste water treatment and even have a huge aquaculture bead filter available to me if I so choose to use it. JohnPTCs success with using bag filters confirms my idea to use those as well.
The filtration will be a work in progress and incorporate many modular filters rather than the sump/scrubbies that most large tank builds use. Sumps collect crap and act as a settling tank. You need to be able to do something with that waste once it collects.
