I have a spring-loaded Pentair check valve after my cartridge filter to keep the solar system from draining back through the filter and pump suction lines when the pump turns off.
I recently had my pump replaced with an Intelliflow and the installer replaced the flapper in the check valve with a Flowvis. Although it is cool and I like the functionality while the pump is on, I am now getting bubbles gurgling into the filter when the pump turns off and the filter drains right away, although the pump doesn't drain enough to lose prime overnight. I can see air in the cover of the Flowvis too.
Now a lot of other plumbing was changed at the same time, but the filter was not touched. Is the Flowvis the culprit? Could it be? Can you put Jandy flappers in Pentair valve bodies?