API High Range pH Test Kit API High Range pH Test Kit measures the pH level in fresh and saltwater aquariums. Used to measure pH changes in marine aquariums, aquariums with African cichlids, and very alkaline tap water. High Range pH Test Kit reads the pH of water within the high range of 7.4 to 8.8. Maintaining the aquarium at the proper pH ensures optimal water quality. The pH should be tested weekly, since natural materials in the aquarium (such as fish waste and uneaten food) can cause pH changes. Recommended pH Levels A pH of 7.5 is ideal for most live-bearing fish, such as mollies and swordtails. Goldfish will also thrive at a pH of 7.5. African cichlids prefer a pH of 8.2. Marine fish and invertebrates require a pH between 8.2 8.4. To raise or lower the pH of a freshwater aquarium, use API pH UP or pHDOWN. API PROPER pH 7.5 may be used to automatically adjust and hold pH at 7.5. PROPER pH 8.2 may be used in African cichlid and saltwater aquariums.