Keep your fish healthy and thriving by testing your aquarium water's PO4 3- levels regularly with this easy-to-use API PHOSPHATE TEST KIT for freshwater and saltwater aquariums. Testing water parameters weekly helps prevent invisible water problems that can be harmful to fish. Phosphate enters the aquarium from fish and invertebrate waste and decaying organic matter, such as dead algae and uneaten fish food. Excess phosphate contributes to unsightly algae and green water blooms. In saltwater, excess phosphate can inhibit the growth of hard corals. API PHOSPHATE TEST KIT for freshwater and saltwater aquariums contains two phosphate test bottles, test kit instructions, one capped glass test tube, and two color cards to accurately measure phosphate levels in fresh and saltwater aquariums. With API Aquarium products, its easy to keep a beautiful saltwater, freshwater or reef aquarium. For over 50 years, API has been creating innovative, research-driven solutions that make it easier to care for your fish and aquarium. API Aquarium Treatment Supplies are designed to work in conjunction with each other to provide best results to control algae, promote healthy bacterial growth and help control and cure fish diseases and conditions such as ich and fin rot. They work to provide a safe, hospitable environment for fish such as tropical community fish, cichlids, goldfish and more. With API, you can spend more time admiring your fish, and less time scrubbing your tank. Make sure to use all products as directed in order to ensure the best results.