I see. Thanks, John. The reason for my asking is I always wonder how long would a tank like this last.
I am talking merely volume of fish over volume of water. Just shooting in the dark, this is about 10x-100x more than the 1 cubic inch of fish per gallon rule of thumb. I know this is doable short term with a tremendous water turnover and a very large sump but over long term... that's what I wonder.
Cuz in some of my tanks too I run over 1 cu inch over gallon and while my sumps are 2x-5x bigger than the volume of my tanks, I wonder what's the turnover to shoot for so the fish thrive, not survive. Naively and crudely thinking, I'd think the turnover should be a few minutes, that is say at 2 min the incoming water should be 30 x the tank volume in one hour.
So in your case, I'd probably be ok to experiment like this with a 1200 gal sump attached to your 600 gal tank and 30 x 600 = 18,000 GPH, which however would blow all these fish around like in a hurricane... Just looking to learn, mate, if you will to share your expertise.
Perhaps one could get away with a 4 min turnover and 9,000 GPH which is still very strong flow in a 600 gal but a lot more manageable by the fish.
I wonder what Phil would tell us
Oddball
. He'd be concerned with the brown blood disease, I am sure, at the very least, with any lesser overall water volume and lesser turnover.