Filter making a dripping sound

We have a Jandy filter which is right outside our master bedroom window. When the system is not running it makes a dripping sound at night which is keeping us up and quite annoying. To solve this so we can sleep I have to release the pressure before we go to be and remember to close it back up in the morning. Have replaced the check valves and main O ring on the filter yet it hasn’t stopped it. There are no visible water leaks and am totally perplexed as to what would cause this dripping sound. Also replaced the breather tube assembly.  Any suggestions?

Peter