Hmmm based on my calculation it should be enough room to hold excess water. I will have a check valve in the return lines so in case if power failure if the check valve works like it supposed to... there should be no water coming back to the sump ( I pray that it works
The only excess water coming back to the sump is the top 1 inch or so from the tank thru the overflow. Taking into account the thickness of the 3/4 in acrylic I should only have roughly 15 gal of water coming back down from the tank. Plus another 4-5 gallons or so from the drain pipe and the overflow box.