The pH scale is a logarithmic one that is used to express the acidity of a solution. It runs from 0-14. The acid portion of the scale runs from 0-6.9 and the basic portion runs form 7.1 -14. A pH of 7.0 is exactly neutral. Each unit on the pH represents ten fold difference in hydrogen ion concentration; thus, freshwater aquarium fish including discus fish that are kept in an aquarium with a pH of 4 is ten times more acidic than one with a pH of 5, while an aquarium with pH of 8 is 10,000 times less acidic than one with a pH of 4 ( or 10,000 times more basic).
Changes in Water pH Can Affect Metabolism of Freshwater Fish
The pH of water constantly changes. However, buffers are used to resist changes in pH and consist of a weak acid and its salt. For example, the body fluids of all vertebrate including fish are buffered so that their pH will remain constant and approximately neutral at a pH of about 7.4.
This is extremely important in view of the fact that their metabolism is dependent upon the action of many enzymes that catalyze chemical reactions. These enzymes function best at a neutral pH, and if their bodies were to deviate from neutrality, then enzymatic activity would stop and metabolism would cease.
Changes In pH Are Common Causes of Fish Illnesses Diseases and Even Fatalities
Metals, ammonia, hydrogen – sulphide and other chemical compounds increase in toxicity with rising pH. Therefore, freshwater aquarium fish environments should be free of all the above. For example, at concentration of 0.01 mg/litre of hydrogen sulphide, fish lose their equilibrium and are subjected to sublethal stress. Although Frequent exchange of water can prevent building up of metal, hydrogen sulphide and ammonia, keep in mind to change it slowly as it causes a lot of stress on your fish. Further, increasing water pH can also reduce metal, ammonia and hydrogen sulphide toxicity. Maintaining a stable pH however, is generally more the way to go.
Conclusion and Recommendations
Based on findings, Phosphate buffers are commonly used to lower pH, however, there are many other commercial preparations that are available for adjusting the pH of an aquarium. Simply filtering water through Peat will also reduce the pH, as well as the hardness, and is commonly used by aquarists to condition water for certain species. Adding deionized water to your aquarium will also reduce the pH by diluting out carbon buffers that maintain neutrality. Regular routine water changes (approximately10% -25% every 2-4 wks) will also prevent a drop in pH and can be used to adjust improper pH. It’s important that you follow the recommendation of the manufacturer of each commercial preparation when using them to adjust changes in water pH.