The Clearwater Total Alkalinity +, when added to your spa water, increases total alkalinity of pool and spa water. An important add-on accessory to have for your pool or hot tub so that you can monitor and keep your water at the correct pH level. It is important to monitor the pH level of your pool and spa water to ensure it is at the correct level. If it is too acidic then the chlorine treatment may not work effectively, the water may cause irritation to eyes in use and it may cause damage to your pool or hot tub. Required if the pH of your spa or pool water is below 7.2. Includes easy to follow instructions for correct application. Suitable for use with any brand of pool or spa.