It wasn’t too many years ago that the home aquarist paid very little attention to the water in an aquarium. Perhaps some of that was due to the fact that most of the water used was collected from ponds or rainwater catch. Now most of us get our water from our water taps. The water has been processed to insure that it is safe for us to drink. Our safe drinking water is not necessarily the best water for fish. Chlorination is usually part of the water cleaning process. That and other chemicals added to our tap water can be stressful and even fatal to some fish.
Fish cannot survive in waters that are too acid or too alkaline. The acidity is measured on a scale that is known as the pH scale, shorthand for potentiometric hydrogen ion concentration. A pH scale starts with the strongest acids measuring pH 1, and ending with the strongest alkali as low as pH 14. In the wild, waters that harbor fish can a range from an acidic pH of 4 to a basic pH of 9. Most home aquaria should be kept near a neutral pH of 7 unless the specific species you have require something else.
There are ways to measure the pH of the water in an aquarium. The easiest is probably the litmus paper strip. To obtain a reading, dip the paper strip into the water and compare the color of the paper with a chart. This is a fast and easy method but can be inaccurate. The chemically treated paper can be affected by age and storage conditions.
A better and more accurate way to test the water is to obtain a kit that provides a vial and indicator chemicals. Water is collected in the vial and then the chemicals are added. The water changes color to indicate the pH.
Besides the source of the water there are other factors that can affect the pH and the degree of hardness of the water (DH). The aquarium ornaments we add to our tanks can slowly leach out calcium and magnesium salts. The ornaments include aquarium gravel, stones, or metals that are place in the water.
Prevention and cure of a pH or DH problem starts with using only aged water. That is water that has been collected and allowed to sit in a loosely covered pail for a day or two before adding it to the aquarium. Another preventative step is to buy aquarium gravel approved for aquarium use by being pH and DH tested. Rocks and stones should be of a non-metallic nature and free of limestone.
Before placing anything in an aquarium it should be washed and allowed to soak in clear water for a few days. The water should be tested before and after the soaking. If the pH or DH changes discard the object or try treating it with a mild solution of Hydrochloric acid then rinse thoroughly. Try the soaking and testing again. Your fish will thank you.