Overflow Boxes

[drew00c]

This might be a really silly question but if an overflow box works with gravity what is to stop the water flow into the sump if there is a poweroutage?

 

[Chris_150G]

Because the power is out the return pump will no longer work. So the water level in your tank will drop as the overflow continues to drain water out without any coming back via the return pump. Once the water level in the tank drops below the overflow box the water will stop draining out. So your sump water level should be low enough to allow for the extra water that will flow down in a power outtage. I call it the flood test. The tank water line will drop an inch or so and your sump water will rise many inches. The amount will depend on the ratio between the size of the tank to the size of the sump.

 

[Smitty]

Once the siphon breaks because of the water level getting too low in the tank.

 

[SeaBee]

Mine just stops once the water drops below the skimmer opening, no loss of siphon. If you want to test it, and you should, just unplug your return pump.

 

[dcantucson]

You should test it anyways.

 

[drew00c]

Ok this makes sense lol, im still thinking of if a sump is crucial for a tank, ill figure this all out when the time comes to make my purchase