Testing the Waters In order for fish to thrive, water must be similar to that which could be found in their natural environment. Poor water quality can cause fish stress, illness and even loss. Most common water quality parameters are Ammonia, Nitrite, Nitrate, and pH. All may vary over time and all are invisible to the eye which is why it is important to test weekly. Testing aquarium water weekly will aid in keeping your most important water parameters within the proper range for your aquarium. Choose from a wide range of API testing options, such as our popular FRESHWATER MASTER TEST KIT or 5-IN-1 TEST STRIPS, for accurate water evaluation. Regular testing will help you easily determine your aquarium conditions. Dip and Read Just dip a 5-in-1 TEST STRIP in your aquarium, swirl twice, and compare to our color chart for fast and accurate results. Pick One (or Two) Need to check your phosphate levels? What about ammonia? API offers specific test kits to test many different parameters, from general hardness and copper to pH and nitrate. Grab the one you need for a streamlined approach to testing. The Scientific Approach For more detailed analysis, use the FRESHWATER MASTER TEST KIT, POND MASTER TEST KIT, SALTWATER MASTER TEST KIT, or REEF MASTER TEST KIT for precise readings of parameters. Safety Information Please Read Instructions Before Use Ingredients Testing Solution, Instructions, Test Tube With Cap, Computer Analyzed Laminated Color Card. Directions pH should be tested weekly, since natural materials in the aquarium (such as fish waste and uneaten food) can cause pH changes. When keeping livebearers, goldfish, African Cichlids, marine fish, or invertebrates, use the API HIGH RANGE pH TEST KIT.