I was going to make one, then saw a pool cooler on mistcooling.com and purchased it instead. It is a tower design with 4 staggered rows of holes for about 4' from the top. My water temp was about 94, I installed the cooler and let it run from say 3pm to 7:00am. The water spray was very refreshing in the 100+ heat we had. The next morning at 7:00am the pool was down to 83 and i had lost maybe 1/2 to evaporation. I took off the cooler and then put it back on at around 3pm again because it was so hot outside. The weather cooled off last night (got down to 80) and my water temp this morning when i removed the cooler was 80 on the dot. Got to say with the cost involved with a heat pump or chiller, cant beat $30.00 and a little evaporation.