The spa return check valve is there to prevent draining back to the pool WHEN THE PUMP IS OFF AND NOTHING IS RUNNING.I will leave the spa running and see if it stabilizes and post results thanks.
2nd I had to drain some of the pool and refill and noticed the spa was low every morning even after not running.
3rd I started using the spa last night and lost around an inch of water in 30 min
With pump on or off?
You lose some water over the spillover when people go into the spa.
You need to be more specific on the conditions during the water loss?
The one circled the gasket was replaced recently. That’s the electrical one.I would check that your return diverter is not leaking some water back to the pool in SPA mode.
That is the SPA MAIN DRAIN which is different then the RETURN valve discussed in post #30.Ok I grabbed a better picture this is in pool mode currently as seen in the picture
That offset not perfectly closed SPA MAIN DRAIN will suck water out of the spa while in POOL mode and cause your spa draining when the pump is running.Final spa picture of water level after the pump has been running for 6 hrs on Pool