So early yesterday evening, I cleaned the pool, the water was a bit low, so I topped it off to where it should be, set the pump timer for 12 hours and left it alone. Apparently, there was a storm during the evening, and when I went out to look at the pool, the water was a few inches LOWER than where I left it. The skimmer was full of pine needles and leaves, so I cleaned those out. I can see water trickling out of the drain hose, but the valve is set on filter. I set the valve to CLOSE and water still trickles out. The ground and street don't look like water has been draining overnight. I'm at a loss as to where the water went.
I did look around the exterior of the pool looking for a leak, but I couldn't see any (but I had just rained last night).