One way check valve on return pump...do you need it?

[KellyCorals]

Hey I was wondering if anyone know if I have to install a one way check valve on my return pump? I’m hard plumbing the system and My outlets sit below the water line and I don’t know if it will try to “back flow” if the power to the pump shuts off. Thanks I’m advance if anyone has any input!

Here is a picture of my pump return

Here is a picture of my return pump with the check valve installed...it’s kinda bulky and don’t want to use it if I don’t have to...

 

[DivingTheWorld]

It may backflow a little. But you should design your system so that your sump can accomidate the extra water. Check valves will fail. I installed a Spears true union check valve on my tank and it failed from day 1. I wish I had never bothered.

 

[JumboShrimp]

Agree with the thought that the sump should be able to handle a reasonable amount of back-flow water if the pump cuts out— but as perhaps a last resort. Couple that with the return nozzles not being so far under the surface that they will drain gallons and gallons before creating a siphon break. (I have my nozzles breaking the water surface at all times, plus have the check valves, plus have extra room in the sump, so hopefully I am covered 3-ways.) You can also research here on R2R where to drill a tiny nozzle/lock-line hole to cause a siphon break.

 

[ca1ore]

Before my 2020 junk purge, my closet of misfit ‘toys’ included all sorts of check valves. Disadvantages outweigh advantages.

 

[monkeyCmonkeyDo]

The toilet flap clear ones are best but i agree no check valve and just have enough volume.
D

 

[mdb_talon]

I would not trust the check valve either. I always drill an anti-siphon hole in my plumbing and keep at least one nozzle high enough to break siphon before sump floods.