API Phosphate Test Kit
The API® PHOSPHATE TEST KIT tests levels from 0 to 10 ppm so that you can easily monitor the condition of your aquarium water and may be used in both fresh and saltwater aquariums.
Phosphate (PO4) can enter your aquarium through tap water, fish waste, and decaying organics such as uneaten food and dead algae. Excess PO4 contributes to unsightly algae and green water blooms, and in saltwater, excess phosphate can inhibit the growth of hard corals.
Why should I test for phosphate?
Phosphate enters your aquarium through fish and invertebrate waste, and excess phosphate can cause problematic conditions in your tank. Use the API PO4 test kit to test for high phosphate levels weekly. It may be used for both marine (saltwater) and freshwater aquariums.
More details on this product, including full instructions, can be found HERE.