Nutrafin pH Wide Range 4.5 to 9.0 for Fresh and Saltwater, 100-Tests Suitable for freshwater or marine aquariums to establish the right pH range for your fish (4.5-9.0 Determines general range of pH in your aquarium Helps you determine proper environment type for your fish Works to provide a healthy and clean living environment for your fish Easy to follow directions; Contains 100 Tests