Water Hardness

Water Hardness

The word Aqua means water. Most of the words accommodating �Aqua� are related to water, and so is the word Aquarium, a tank filled with water, sustaining aquatic life within it. Therefore, just like aquatic pets, water is one of the key elements present in an aquarium. The health of an aquarium�s inhabitants is contingent upon the quality of water. The quality of water is determined by the level of its different parameters such as, Temperature, pH, Trace Elements level, etc. Water hardness is one such factor influencing the aquarium water quality. This page takes up some of the key aspects of Water Hardness.

Water Hardness � Introduction. Water in general is classified as �Hard� and �Soft� Water. The hardness of water depends upon the proportion of minerals present in it. The more the amount of minerals present, the harder the water. Water Hardness has further two types, General Hardness (GH) and Carbonate Hardness (KH). Calcium & Magnesium are the two key elements contributing mainly to the overall hardness of water. For most of the Marine Aquariums, Calcium is recommended within a range of 350-450ppm and the Alkalinity (Water Hardness) range of 8-12dKH.

Water Hardness � The Types.

General Hardness (GH). Also known as Permanent Hardness or Alkalinity, General Hardness, is caused due to the presence of the divalent metallic ions of Calcium & Magnesium in water. Undesirable GH levels can adversely affect the normal functioning of Internal Organs, Growth, & Fertility in most fish. You can increase the GH of water by adding Limestone or Calcium Carbonate to the water and can reduce it by adding Peat Moss to Filter, by using commercially available Water Softeners, or by mixing Tap Water with Reverse Osmosis (RO) Water. Water Hardness levels are categorized as per the following table:

Water Hardness Reading Water Hardness Category

0-4dH or 0-70ppm Very Soft

4-8dH or 70-140ppm Soft

8-12dH or 140-210ppm Medium Hard

12-18dH or 210-320ppm Fairly Hard

18-30dH or 320-530ppm Hard

30dH or 530ppm+ Very Hard

Carbonate Hardness (KH). Also known as Temporary Hardness (can be removed by boiling), KH is a result of the presence of Carbonate or Bi Carbonate Ions in the water. These ions act as Buffers and tend to stabilize the pH of water. Therefore, KH represents the Buffering Capacity of water, and is directly related to the pH of water. The more the KH of water, the higher will be its pH and more will be its buffering capacity. You can increase the KH of water by gradually adding Baking Soda or the commercially available Water Softners. You can decrease the KH either by diffusing Carbon Dioxide or adding Reverse Osmosis Water to the Hard Water, till the desired KH level is not achieved.

Water Hardness & Aquatic Pets Compatibility Table

Water Hardness (GH & KH) Range Some Suitable Fishes

0-50ppm Discus, Arowanas, Elephantnose, Neons, Cardinals, Live Plants, & South American Fish

50-100ppm Most Tropical Fish, including Angelfish, Central American Cichlids, Tetras, Botia, & Shark

100-200ppm Most Tropical Fish and Live Bearers, including Swordtails, Guppies, Mollies, & Goldfish

200-400ppm Rift Lake Cichlids, Goldfish, & Brackish Water Fish

Adjusting Water Hardness in Marine Aquarium.

Increasing Water Hardness.

Adding Sea Water. Add a small quantity of Seawater in the tank to get the desired level of Water Hardness.

Adding Calcium Products. You can convert Soft Water to Hard Water by adding Calcium Carbonate Accessories such as, Corals or Limestone, to water. Alternatively, you may use Calcium Hydroxide with a deep Sand Bed (fine Aragonite).

Commercial Water Additives. Many products such as, Sea Buffers (a mixture of Carbonates, Bi Carbonates, & Borates), are available in the market to boost the hardness of aquarium water as well as balance the Calcium�Alkalinity level without disturbing its pH.

Adding Baking Soda. Small portions of Baking Soda can also be used to increase the Alkalinity of water temporarily, but it is not advisable when the other safe methods are available.

Calcium Reactors. Calcium Reactors are very effective and a convenient way to balance the Alkalinity of the aquarium water. Calcium Reactors are the vessels filled with Calcium Carbonate. To do the balancing act, Calcium Carbonate slowly dissolves in the presence of Carbon Dioxide.

Reducing Water Hardness. Reverse Osmosis, Peat Moss Filtration, adding Soft Water, raising Carbon Dioxide level, and employing commercially available Water Softeners are some of the key ways to reduce Water Hardness.