The Insta-Test® Phosphate pool and spa strips provide very quick and reliable water test results. Phosphates are important contributors to algae growth and can reduce the effectiveness of some automated chlorinated systems. This unique test allows the user to read low range test results by looking down in the reacted sample tube. Test instructions are on the bottle along with a color chart. Keep phosphates below 300 ppb to avoid problems in your pool or spa equipment. LaMotte company has over 85 years of experience in water analysis and offers a complete line of Insta-Test® strips for the pool and spa owner"s needs.