Suggestions to eliminate acid check-valve plugging? Have a Pentair IntelliPH acid dispenser with a tank-mounted Stenner pump. The Pentair 522513Z check valve plugs once a year with what looks like fine black plastic shavings. I see a very small amount of black debris in the acid tank, but seems too difficult to attempt cleaning the tank. The 522513Z check valve has an internal ball. Anyone have experience using a duckbill check valve on 32% muratic acid? Considering a Stenner UCDBINJ duckbill, which looks like it may be more resistant to plugging. Pressure ratings on the check valves are 26psi to 100psi, but I don't know how much pressure is required on the acid pump side to push acid thru. Seems high when I test the valve. Doesn't seem such high pressure is necessary since the check valve is installed downstream of the filter, just ahead of the SWG.