A rough feel on the sides or bottom of your hot tub is caused by scaling. This is when the calcium comes out of solution and turns into a solid. To prevent scaling, it is important to keep your total hardness between 150 and 200 and your alkalinity between 80 and 120. To remedy scale, it is important that you do not drain your hot tub. You would use a pH & Alkalinity Decraser to lower your pH. This should result in the calcium returning into solution and resolving the problem. It is important not to decrease the pH below 7.2. It may take a few days for the calcium to go completely back into solution and you may see cloudy water for a few days before you get clear water. Once you resolve the problem, it is recommended that you use Leisure Time Defender to prevent future scale buildup on a weekly basis.