I don't know what the "official" temperatures are, if any. I work in outpatient rehab services in a wellness center, which has a fitness pool at 83 degrees, a therapy pool at 92 degrees, and a hot tub at about 104 degrees. Our therapy pool is a pretty good size (about 30 ft by 40 ft, 3ft depth to 5 foot depth), but does not go terribly deep, so sometimes we take taller patients into the fitness pool; however, the fitness pool is kept at a temperature appropriate to hard athletic activity, and sometimes patients with back pain will spasm straight back up in the cooler water. I spend four hours a day in the water, and yes, we do notice temperature changes of even a degree or two. Most patients, and especially slow movers, elderly, or children, do better in a warm pool (92+); patients with neuro dysfunctions such as multiple sclerosis may do better in the cool pool.