So this is the plan i have 7 120 gal tanks and 5 220 gal tanks.There is 2 6"x6" over flows on the back of the tanks that goes all the way to the bottom with the glass begging drilled with a 1"3/4 return pipe to sump. At this point all of the tanks are on there own sump, which means lots of testing and space usage. My question is if i put them all on one sump, which would be 900 gallons, could i use 1 or two big pumps like the dolphin 8200 gph to feed the water back to the tanks. So the way i see, i would have 2" pipe going along the base of the tanks with T's coming off reducing to 3/4" for the feed. Now the back flow to the sump would be gravity feed. The flow rate calculator tells me each tank would recieve 560 gph. So would each 3/4" pipe need a ball valve to ajust rate, and would it need to be closed loop? Please view drawing for over view.