Test results
OK, here it is.
I removed the check and left the CSV in place.
I ran and flushed everything for a while until I was satisfied that there was no more air in the pipes.
I closed the house valve and shut off the breaker. Tank was at 68 PSI.
By morning there was zero pressure in the tank.
Today I did the same and checked the pressure at 30 minutes and 1 hour.
At 1 hour, the pressure was down to 56 PSI. The pump starts at ~55.
So here it is. I have a leak that drops a Flex-con WS120 tank from 68 to 56 PSI in 1 hour.
The pump is actually ~60 feet down the well.
Here's a possible fix to reduce pump cycling.
Reinstall the check with a T before and after it.
Across the T, install a small check with a regulator to allow only 3-5 PSI from the tank to the pump while the pump is off and things are leaking. This will reduce the leakage flow rate but not restrict normal operation. The pump line will stay prssureized to avoid air getting in but the pressure will be greatly reduced when off.
Thoughts?
Also, My wife and I agree that something will have to be done about the pump. At 60' down, can I change it myself?