OK..bonehead move of the season (so far).
We've had excessive rain here. Yesterday I woke up to find the water level was well over the top of the skimmer. This was around 9am. My pool has the Jandy Aqualink PDA system and is programmed to come on at 11am. So, at 9am, I switched the multiport valve to waste, turned on the pump manually and lowered the water to below the top of the skimmer. Shut the pump off and went out on errands. (does anyone notice I've missed a step??)
At 130pm, I came home to find the pool about 12" lower than when I left, the pump running merrily away with no water in it, and the pool water level, of course, below the bottom of the skimmer. The filter was still in the 'waste' setting. So, my perfectly balanced water was in the sewer, and I had to add water to get the level back where it should be. Goodbye to perfectly good stabilizer I had just added, salt, chlorine, etc. etc.
Still, this is the first time in 4 years I've done this...and hopefully the last. I hope I haven't taken years off the life of my pump.