You need to stop and rethink this. The calculator you used tell you how much flow you should have in your tank from all sources (return pump and power heads).
The hole that is 2" from the top of your tank is a drain hole. It is meant to drain water from the tank to a sump below the tank. You then need a pump to return water from the sump to the tank. That pump needs to match or be rated slightly less than the gallons per hour (gph
) of your drain pipe. If the pipe from the hole in your tank is 1" in diameter then it can drain 600 gph
. If is 1.5" then it can drain 1200 gph
. You need to find a pump that does not exceed the drain capacity. Pumps are rated for a gph
flow at 0' head height and decrease in efficiency for every foot they need to raise the water to get back to the tank. A MAG7 is rated at 700gph at 0' of head height (HH) and 500gph at 3' of HH.
Does that help at all?