I've spent the last 7 years keeping saltwater fish, but have decided to try freshwater instead. My tank is a 200g reef tank with a diy 40b sump. I took out all the baffles in the sump to set it up for fw filtering but I'm not sure what all I need in the sump, or how many chambers to put in it. I can make up to 5 media chambers with 100% flow thru in the sump. -what should I use for bio, and how much? Will be fully submerged. I will be keeping 3 large pacu's from 15" -20" and 2 large cichlids 12". I was thinking 10lbs of ceramic rings should do it, but I really have no idea. -should I run airstones in sump? If so, should I run them in the bio media chamber or a separate dedicated chamber? I know my first stage will be 2 7" filter socks. I run carbon in a fluidized reactor so no need for it in the sump. What other things should I consider for filtration to make the best use of extra space I have? I'm know lots about saltwater, but nothing about fresh so any knowledge is appreciated.