Many factors effect pH. Decomposition of fish waste, excess food and decaying plant matter all contribute to a pH decrease, as does overstocking and poor aeration. Hardness and alkalinity also effect pH. Soft water tanks have a low alkalinity and therefore have difficulty maintaining a stable pH. Soft water lacks natural pH buffers (in the form of calcium and magnesium carbonate). This lack of buffers results in a downward pH drift. Care must be taken to ensure pH never falls below 6.5 in freshwater or 8.0 in saltwater. Below these levels, nitrifying bacteria are inhibited and the bio-filter can "crash". Fritz pH Higher is a liquid buffer that increases pH and alkalinity in fresh, brackish, saltwater and reef aquariums. Unlike many other pH increasers, Fritz pH Higher uses natural carbonates instead of Sodium Hydroxide (Lye) to safely raise pH & alkalinity. The all-natural Fritz method of pH control is exactly the same as in the fish's native habitats. Once the desired pH is reached, use the appropriate Fritz PH Block to maintain the proper level. One teaspoon Fritz pH Higher treats 15 gallons; 1 capful treats 25 gallons. Quick and Easy Reference Increases pH & alkalinity; stabilizes pH and prevents deadly "pH Bounce" Conditions water in freshwater, brackish and saltwater aquariums, reefs and ponds Phosphate Free! Won't cloud or discolor water! Very concentrated, professional formula: Each capful treats 25 gallons in fresh & saltwater Information from Fritz