Sump concern with overflow without electricty

[WhoKnew]

Hello all. My question to the Forum is: I have a 72 Bow Front with an built in overflow box, Manufactures drill for a sump. Okay, I understand the process of the water being gravity fed into my sump tank, than with a pump, it is forced back up into the tank. Seems prety simple. BUT, what happens when the electriocity goes out and the pump stops? In my head, small as it may be, the water from the display tank still is gravity fed down into the sump, and it will flow all over my livingroom.
I know that there is enough SWT builders and users, that there is a way to stop that. HELP

 

[DFW]

It can only siphon water from the overflow box, not your whole tank..

I should add, as the next poster has said, your return lines also siphon water as well, so you limit that any way that you can, often with small hole(s) drilled in return just at, or above the water line. You must keep these holes cleaned out regularly as they can stop up!

 

[Bow]

The overflow box and the returns. You will have to play with the hight of the returns(guessing loc line). The water will siphon until air gets into the line. Some suggest drilling a small hole to in the bottom of them to speed this up, but you have to keep it clear of critters and salt creep. Play with the return lines on your time. Set them where you want them then turn off the pump. Wait and see how much drains into your sump. Be ready to turn it back on quickly if they are to deep. Repeat the process until you are satisfied that the level is good.

 

[WhoKnew]

Thank you all. I see where this is located in my overflow box.