Drilled Tank Question

[Charlie_Tuna]

I am purchasing an acrylic 120 gallon tank, pre-drilled with overflow.

The tank has an additional hole drilled in the bottom for a direct return line.

If I choose to use this return method, should I not be paranoid in terms of power outtage? I have heard that PVC check valves get dirty quickly and can be unreliable.

Would I be better off finding some way to cap this hole, and run my return line up and over, so that I could drill a hole in the return line just under the water level? Is this reliable?

Also, any suggestions as to sump size?

Your help is greatly appreciated!

Charlie_Tuna