I used to worry about high water temps when I first started but not anymore. I’ve grown large healthy great tasting tomatoes with reservoir water temps as high as 85 degrees and as low as 45 degrees with no problem. I put screens to catch and prevent dead broken roots or any other type matter that would drain back into the reservoir and possibly clog the
pump.
Always need to test ph levels every 2nd or 3rd day depending on how good the water in Any given area.