GENERAL HARDNESS AND THE AQUATIC ENVIRONMENT

WHAT IS GENERAL HARDNESS (GH)?

General Hardness, also known as Total Hardness, is a measure of all the dissolved salts found in water. These salts are mainly composed of calcium (Ca) and magnesium (Mg). Calcium and magnesium are the most common metallic ions present in water, with calcium commonly present in a ratio of 3 to 1 (natural environments) versus magnesium. Other metallic ions such as copper, zinc, iron and others affect Hardness but are usually present only in trace amounts and are therefore insignificant.

WHY IS GH IMPORTANT?

The concentration of dissolved salts affects fish in two important ways. Osmotic regulation (equilibrium of the internal salt concentration) and blood calcium levels are regulated by General Hardness levels. The osmotic regulation process that takes place within a fish serves to replenish essential ions in the blood. In water, with higher dissolved salt concentrations, ion loss is reduced. The calcium level in the blood is related to Hardness levels. Hard water species have to excrete calcium whereas soft water species require intake through diet and from their own skeletal structure. It is beneficial to maintain fish at General Hardness levels that approximate conditions which they have evolved in. This will support natural functioning of their osmotic regulatory system.

HOW TO ADJUST GH

Determine the ideal range for types of fish maintained. Use a GH/KH test kit to verify the existing level in aquarium and tap water. Adjust, if necessary, with African Cichlid Conditioner at a maximum rate of 20 mg/L per 24 hours until the desired level is obtained. African Cichlid Conditioner will safely raise Hardness levels and provide a natural 3 to 1 ratio of calcium to magnesium. It will provide increased Hardness levels with the introduction of essential minerals without affecting the pH or Carbonate Hardness (KH). If a lower level of Hardness is desired, the use of Peat or dilution with R/O water is recommended.

WHAT GH LEVEL TO MAINTAIN

The preferred range for optimal fish health and plant growth is between 70 and 150 mg/L. However, exceptions do exist. For example, African Cichlids should be maintained at levels of approximately 150 to 280 mg/L. Discus and certain other soft water cichlids prefer ranges of approximately 30 to 60 mg/L. Maintaining fish within their preferred range will support optimal performance with respect to growth, reproduction and disease resistance. In general, when fish have evolved in extreme Hardness values (high or low), it is recommended to respect their preferred range.

Maintaining a stable Hardness level is best accomplished by a regular water change schedule. By performing regular small water changes as opposed to topping up due to evaporative losses, there will be less accumulation of dissolved salts. If source water is soft, the controlled use of African Cichlid Conditioner and a GH/KH test kit is strongly recommended to obtain and maintain Hardness levels.