Put in a submersible pump (and submersible wiring!). Run the water in the pool through the pump up into the air, like a fountain. That will cool the water as well as aerate it.

Or you can install one that simply keeps the water circulating, so that the heated surface water is brought down and the cooler bottom water is brought up in a regular cycle.

One really cheap way of doing the former is the dive to the bottom, fill your mouth with water, swim to the surface and spit it into the air. If the P-vine asks what you think you're doing, you can tell her you're cooling the pool for her.