Check Valves on Chorinator

by Kathleen
(PA)

Why do you need to have a check valve after the chlorinator? When the pump isn't running the water inside the pool maintains equal pressure on both sides of the pump and filter, so the water is not flowing.

I don't see how water can back feed into the filter.


Hi Kathleen. I'm not sure how, or why, it does but it does. Whether the water moves or whether it's just the fumes that move through the water, I’m not sure. I do know the damage that can be caused by chlorinators and I would sure have a check valve.

Hi concentrations of chlorine can easily damage a vinyl liner. I have seen this happen when the return flow was set to hit the edge of the pool as opposed to going out away from the pool wall. I have also seen liners damaged by leaky returns where high concentrations of chlorine seeped around the edges of the return and came in contact with the liner.

For many years we set up chlorinators for a store we worked for. We plumbed all the filters with flexible PVC pipe. This pipe normally lasts just about forever. We found that the short piece of pipe used between the chlorinator and the check valve would only last a few years before it was eaten up from the inside out.

Seeing what this amount of chlorine could do to PVC pipe made me a believer in check valves and helped me to understand why this water should not be allowed back into the filter.

The valves we installed were between the filter and the chlorinator. I believe this is the proper place to install them.