After the first season with our pool and using the TFP method, I switched over our hot tub from the dry chemicals to the same stuff I use in the pool. So happy with the results. They had instructed us to replace filters every 3 months and drain and fill twice a year. it's been almost a year since I last drained it and made the switch. Water is better, less expensive, and the filters are lasting longer as well. I'm a little sloppy sometimes on checking chlorine levels in it though, I need to get better at it. However, bringing up a hot tub to shock levels is so quick, uses very little chlorine, and clears up in under a day, so its really quick to recover from.