Prevent Sump Overflow?

I just got my first sump filter for my 90 gallon FOWLR. I have a flexipipe return setup in my tank from the sump and i accidentally turned my power off to the filter for less than a minute yesterday and my sump (which is only setup for halfway full) began to overflow. I am guessing that it was creating a siphon from the flexipipe and was wondering how to prevent this in the event of a power outage. I am afraid to goto work now and leave it with all of the storms that we have been having in Ohio lately. Any suggestions?

I included a picture of the flexipipe setup through my tank. It was dirty then but is not now!

 

You need to drill two 1/8" holes on each return line just below your water level in the display tank to break the siphon. Also you need to fill your sump up to the height that allows the water from the DT to back flow into the sump with out spilling out. This is a trial and error process. Mark the sump return section where the sump does not overflow when there is no power.

 

you can also put a check valve on the return.snails and high alk/ca levels are notorious for undoing your work on the outputs. of course check valves can fail too, that why i use both. Your ultimate win scenario involves leaving a solid air gap.

 

Drilled holes and check valves can and do fail even with maintenance and cleaning. It does not have to be a catastrophic failure, even a grain of sand on the check valve seat will flood given time.

Place your return so it is just below the surface so in a power outage only a small easily calculated amount of water backflows before the return is exposed to atmosphere. nothing beats an air gap for backflow prevention and it requires zero maintenance. Do it right the first time and you can sleep soundly at night.