General Hardness (GH), from the German Gesamt Haerte meaning total hardness, is, most simply, a measurement of the sum of hardness cations, primarily calcium and magnesium, in solution. [This differs from total dissolved solids (TDS), which is the measurement of all conductive ions in solution.] The general hardness of a solution is most often measured in degrees of general hardness. So-called “hard” water has a high GH relative to “soft” water. The GH required in an aquarium is dictated by the geographic origins of the plants and fishes in the system, and is best determined by doing preliminary research or reading a book on the subject. Botanica GH+ provides the ions necessary to increase general hardness. This product should be used in conjunction with an accurate test kit. General hardness is important because aquatic organisms have evolved under relatively stable conditions, barring seasonal and temporary changes in water chemistry. Therefore they do best over a fairly narrow range of general hardness values. In fact, many species of fish may not breed successfully nor even survive for extended periods of time if the hardness is not within an acceptable range. Plants are no different; extreme values in general hardness may hinder plant tissue production, and can eventually kill the organism. Botanica GH+ and KH+ are best used with reverse osmosis and/or deionized water during initial tank fill-up or during water changes, although dechlorinated tap water will work. Depending on species, changes in GH and KH over a period of several weeks may simulate seasonal variations that many fish use as spawning cues, and that cause many plants to flower and reproduce.

This product is primarily meant to be used on initial set up and when performing water changes. Each 5 ml of GH+ raises the general hardness of 5 gallons purified water by 2 degrees of General Hardness (dGH). See the chart below on the recommended GH of aquarium water prior to using this product. Then, add GH+ and mix until the target general hardness is achieved. To decrease the general hardness in an aquarium, dilute with distilled, deionized or reverse osmosis purified water. This product should be used in conjunction with an accurate GH test kit.