I have a combination pool/spa that runs off the same pool pump. When the pump in running, water is continually pumped to the spa and delivered thru the spa's fountain and then the water is returned to the pool via an overflow opening in the spa. Earlier this week, I came home from work and noticed the spa's water level was at approximately 50% capacity. I immediately turned the pool pump on and the spa filled and then overflowed back into the pool as usual. The next day, the same thing happened... and the next day and the next day.
Does anyone know what could be causing/allowing the spa to drain back into the pool like this? I've checked all the equipment valves and they all appear to be set in the same position as always.