Return pump siphon

[dioscrummy]

So it just struck me, while it probably should've been obvious; if my return pump turns off. It turns into a siphon. Was adjusting the pump for my new sump system, and when I unplugged it my tank level dropped to three or 4 inches.
What should I do to prevent my sump from over flowing in case of a power outage?

 

[Fresh2o]

You could drill a small hole in the return pipe (nozzle, elbow) just above the water line. When the pump stops, the hole will allow air to get into the return line and break the siphon before it starts. The hole does not need to be large (~1/8"). Drill the hole at an angle so that that water that shoots out of it when the pump is on is pointed downward. If you are paranoid about algae, slime, or inverts plugging the hole, drill a second one.

 

[dioscrummy]

Would this cut into my powerhead pressure? My return will basically generating all the flow for my tank(30 gallon)

 

[54seaweed]

most over flow boxes will only allow so much water to flow down to the sump in power outage, if your return pump is pulling water in on a outage it sounds like you may need a lift pump it will break siphon during outage and start at powering on .
I had a similar issue but it was not my sump overflowing it was my tank overflowing the siphon in my overflow would not start till I added a lift pump . its amazing how many water issues those little pumps help resolve .

 

[Fresh2o]

Would this cut into my powerhead pressure? My return will basically generating all the flow for my tank(30 gallon)

The effect on pressure should be negligible. There is no change to the plumbing as in adding a T or changing diameters or introducing an obstruction. The water coming out of the hole should be a small stream.