Here is the temporary setup that I have going until I get my new area done. The feed line is 3/4", the return 1-1/4", there is a Tunze circulating pump in the lower reservoir for stirring, and the lift pump is a Mag 3. The pumps are on a digital timer and run for 2 minutes, 3x a day. The upper reservoir is a 5 gallon bucket that probably holds about 4-1/2 gallons at the overflow level, and the lower one holds 20 gallons. There is a single feed line on this one with a valve at the far end for purging air, flowing the system, or whatever (like the bottom drawing in heady's post).