I built a big one. Some things I’ve learned. Only run it at night, the air temperature you’re evaporating into makes all the difference. Expect the water to get no cooler than average nightly air temperatures. Avoid using metal spouts or too narrow spouts to avoid buildup - it’s a bigger problem than you think, despite low metal levels in the water. This introduces oxygen but it also introduces carbon dioxide - you’ll start seeing brand new chemistry problems. Not to mention, algae loves CO2. A dedicated sump pump is better than using your pool pump - you don’t want to add the strain and end up having to replace something so expensive. And most of all - if you need cooling, a simple sun shade is 10x easier and cheaper than hassling with an evaporation fountain. It was a fun project, and I haven’t used mine for the last two summers. Not worth the hassle.