High Phosphate levels encourage algae growth in both freshwater and saltwater ponds and aquariums. Phosphate is a major nutrient for plants and phosphate levels increase from decaying organic matter and fish waste. Algae is unsightly in freshwater ponds and aquariums and in saltwater environments it can inhibit the growth of corals and other reef building organisms. The API Phosphate test kit will easily and accurately measure the phosphate level in your aquarium or pond. Kit includes two bottles solution, Doc Wellfish Flat Bottom Test Tube, Directions for use and problem solving tips. 150 tests.