Is it typical and customary in a pool/spa combination for the spa water level to drop 1" in a 24hr period after shutting down the equipment? My spa is connected to the pool with a water fall back into the pool when operating. After the filter shuts down, the next day the water level in the spa has dropped 1". I am a new pool owner and do not have any bench marks to compare this in order to determine if I have a leak or this is acceptale. Pool/spa is approx 15,000 gals.