Nice set up, thanks for all the info, I can get my hands on 3 brand new 35 gallon drums, being that my tank is 320 do you think I would be ok with 3 35 gallon drums instead of 3 55 gallon drums? How much K1 do you have in that 55 gallon drum? I was going to order 4 cubic feet if I go with the 55
Honestly, three 55 gallon drums is WAY overkill. That's ok if you want to do it that way though.
For comparison's sake: I run a 300 gallon, heavily stocked with Malawi fish.
I have one layer of coarse Poret as the prefilter. I have about 5 gallons of bioballs. That's it, and I have a heavy bioload. There' s dimishing returns on over filtration.. For example, I could pump from my sump to 55 gallons of pond matrix, and it wouldn't make a difference at all, because my system can handle all the nitrates/ammonia as is. A key is to occasionally vacumm the gravel and occasionally clean the crap out that settles in the sump. And water changes of course.
If you really want to overkill on filtration, focus on stuff that removes nitrates.. Either set up a pythos plant to remove nitrates, or a dentrifier, something like that.. Those actually remove nitrogen wastes. Scrubbies/bioballs/etc just help convert ammonia and nitrites to nitrates, which is good, but the "pollution" is still there until you do a water change (and obviously Nitrates are less toxic).
Like I hope this doesn't sound like a lecture, but IMO, a lot of money and effort spent on overfiltering is not necessary and could be better spent elsewhere.