Your fishy mates deserve a healthy home. A good grasp of the aquarium nitrogen cycle will help you create it! Food, fish waste and plant debris break down into ammonia, which is toxic to fish. Nitrifying bacteria in the filter and gravel bed convert ammonia to toxic nitrite, then other bacteria convert nitrite to nitrate. While low doses of nitrate are non-toxic, long-term exposure to high doses can stunt growth and cause stress and vulnerability to disease. Maintain ideal water conditions with fish tank test kits from brands including API and Interpret. Convenient test strips, drops and tablets make it simple to monitor water, detect changes and treat potential problems. API’s Freshwater Master Test Kit for 800 tests and Interpret Master Tablet Test Kit with pharmaceutical grade tablets both analyse pH, ammonia, nitrite and nitrate levels. Browse fish tank test kits for individual compounds, test and treatment packs, plus aquarium starter kits.