My son just turned six last month and he has been taking spas with me for over a year and enjoys the water between 99-100 degrees. I only let him in the spa when I'm in it with him, and we only take a twenty minute spa. I use the twenty minute pump timer to let us know when the time is up, and so far everything has worked out fine. I tried bringing the temperature up just a little, but he gets out and sits on the edge if the spas goes above 101 degrees. He knows how to swim, but I always keep the cover locked on the spa whenever it's not being used or monitored.