serious problem
 

Hi i have a fish tank with sump the tank is 55g and drilled at the top if my pump goes out for any reason the drain will keep draining into my tank then eventully overflow this is bad beacasue i live in a buildiing anyone have any ideas for me :(

Drill a small hole near the top so that when the top tank drains to a certain level (not much) air gets into the pipe and breaks the siphon.

You live in a building!! wow your so lucky!! ol jk, you had a typo.:lol:

Can u explain
 

I Dont understand what your trying to say sir :( can u please explain a little better or show a picture :-(

http://www.melevsreef.com/plumbing/refugium.gif

note the little dot on the left at the top of the return pump. When the water level drops to that point, that hole lets in air and stops the flow of water from flooding your sump.

ty so much