Kalkwasser and check valves

[jonesdeini]

I have a 20 gallon tank on the ground with RODI water in it, and a neptune PMUP connected to an avast klak stirrer. I have a check valve on the 1/4" tubing from the PMUP to the stirrer so water does not flow back into the 20 gallon. However every few months my check valve stops working and the contents of the stirrer are syphoned back into the 20 gallon. I googled for this and only found one other person with this issue and most people on that thread basically told him he was doing something wrong(but not what)

It is very possible I've over looked something but this seems like it should be a simple thing. The only explanation I can think of is that the klakwasser is eating away whatever makes a check valve work until it fails

Has anyone else had a similar problem? Is there some better type of check valve some where that I don't know about?

 

[Gill the 3rd]

My guess is the kalk is building up in the check valve, stopping it from closing. Kalk deposits build up in my dosing tube opening to my sump and I have to clean it about the once a month otherwise it plugs up. I have to think kalk through a check valve is going to plug up pretty quickly