Before my in ground pool, I had an 18' Intex. I built a fountain for it that would spray water 8' high and almost all the way across the pool. It was in full sun and once the water would warm up to 95, I could run it all night and it would cool it off about 4 or 5 degrees. The problem is that once the sun comes up the following day, it heated right back to 95 pretty quickly and running the fountain in the daytime could not overcome the heating effect of the sun so it would warm right back up. So unless I wanted to take a 7am swim...it was practically useless, by the time I would get off of work it was right back to 95/96 degrees.
I now have a 30k gallon in ground, and this is my 1st full summer with it. It is also in full sun, starts to shade out about 6:30pm each day. I am hoping that it will not get as warm as the above ground did...but I know/fear that it will. I have done a good bit of reading...and it would appear that Glacier Pool Cooler will actually cool a pool without using hardly any electricity. There is an upfront cost associated with the unit itself..but the monthly operating cost is next to nothing and it will work during the daylight hours, probably even better if you can put it in the shade somewhere. I refuse to have this big, nice new pool that heats up to 95 degrees....so I foresee something like this in my future.
Pool Chillers and Pool Coolers by Glacier Pool Coolers