About This Item Destroy bacteria and algae and get a visibly brilliant sparkle that lasts! Traditional chlorine products contain cyanuric acid CYA. When too much CYA builds up it can cause overstabilization or chlorine lock cloud your water and cause algae growth. The slow dissolving Cal Hypo formula in HTH Chlorine Skimmer Tabs provides a steady source of available chlorine without adding extra CYA for beautifully clear water. This product is great for all pool types including vinyl lined pools and salt water systems. How To Use HTH Chlorine Skimmer Tabs Place tabs in an empty skimmer basket Follow the on pack instructions according to your pool size. Make sure the skimmer basket is free of all other water treatment products before adding tabs. HTH Chlorine Skimmer Tabs work great with the HTH Skimmer Basket Insert. After one day of use test free available chlorine FAC residual with HTH Multi purpose 6 Way Test Strips sold separately. Do not enter your pool until the free available chlorine residual is 1 to 4 ppm parts per million. About HTH Pool Care HTH was developed with the pool owner in mind. We know that maintaining your pool water can be a lot of work. That is why we are here every step of the way helping you clear the uncertainty from pool care. With economical, easy to use solutions HTH is designed to work hard so you are prepared to tackle whatever life throws in your pool. From balancing your water to treating green water, we offer a full line of products to keep your pool water healthy and your swimmers happy.