How to break a siphon????

[rockybound]

Hello!

I need some advice. I'm going to be plumbing my 45 gallon tank with a refugium below it, which is only about a 10 gallon tank. I'm worried about the power going off and the return reversing its flow and flooding the refugium. The return nozzle is about an inch below the surface of the main tank. What ways are there to break the siphon on the return? Any ideas? Is that needed? There's a picture on http://www.InlandReef.com/ that has a basic design which I am following, except that I'm going to have a Mag 5 running submerged as a return pump. (See the "Typical Plumbing Setup" picture link on the "Plumbing Parts" page) Thank you in advance.

[dennisV]

easy : on the highest point of the loop, drill a hole and stick a tube in it (going up). When the power goes off, air is sucked through the tube instead of water, result : no siphon

[ErikS]

Or you can drill a siphon break in the return line just below the surface of the water. Just drill an 1/8" hole & when the water level drops the siphon will break.