Valve to block water return

[tired_boy_mike]

Hey guys,
I have a question I hope you guys can help me with.
Currently water flows from my tank to my sump on the bottom through an overflow system. The water is returned back to my tank via a RIO pump. When there is a power outage, water will be sucked back down through the tubing and back into my sump. Is there a valve I can get to prevent water to flow back to my sump? And if there is where can i get one.
Thanks...
tired_boy_mike

 

[prohopper]

You can Install a check valve (one way valve) on your return line but many people do not recommend using one because over time alge buildup may not allow the valve to fully close and water will still flow by it. The best way to prevent water from entering the sump if the power goes off is to drill a small hole above the water line in your return that way when it starts to flow back into your sump air will get in the line and break the siphon

 

[acrylic51]

Like Prohopper suggested you can use a check valve, but it might fail at some point. The best would be to drill syphon holes in your return line just below the water surface.
You can buy clear(see through) check valves that you can inspect at cleaning time to make sure that they are functioning. You could honest use both at the same time for redundancy sake!!!!!