Tetra EasyStrips 6-in-1 Aquarium Test Strips measure 6 important water quality parameters - nitrate, nitrite, hardness, chlorine, alkalinity, and pH. The test strips are designed with the same technology used in medical and scientific laboratories, giving you fast and accurate results. No chemical mixing or glass vials required! Tetra EasyStrips are safe, non-toxic, and simple to use. Just dip directly into your aquarium water and read the color-coded results in 60 seconds or less. For freshwater and saltwater aquariums. It is recommeded to test water daily with new aquariums and weekly for established aquariums.