No use crying over spilled pool water.

Having gotten 7 inches of rain in January, the pool was in serious need of a good pumping out. So I put the spare pump on the top step of the pool, ran the outflow hose into the patio sump (which pumps water out to the flood control chanel), plugged it in, and walked away. A few hours later I unplugged it and went to bed.

The next morning, this was the water level. Notice where the leaf is floating. That's six inches below where it had been the prior afternoon. And this is the lower end of the pool (the deep end of our pool is higher out of the ground than the shallow end, but that tilt hasn't changed in decades so no worries). The deep end, where the filter pump inflow is located, was high and sadly dry, and not able to maintain suction for filtration.

Jon pointed out to me that when the pump is in the pool and the end of the hose is all the way down into the patio sump, it forms a siphon. I know how a siphon works, of course; it just hadn't occurred to me that, in our ridiculously unlevel back yard, the hose was farther down on the sump end than the pool end. Even unplugged, the pump was allowing water to flow out of the pool and (pump out into the ditch) all night.

So I ran the hose the other way and put about 1000 gallons of water from my overflowing rainwater tanks back into the pool. Sigh. Well, it is early in the year, perhaps we will stilll get enough rain to fill them back up again.