Water Hardness Affects Fish Health

Water hardness is an important measurement when determining the water quality, as well as fish health. This also affects the pH level that may become toxic to fish and other life forms in the water.

What is water hardness? It is the concentration of metal ions like magnesium, zinc, iron, and calcium, which come from rainwater. Most water contain only calcium and magnesium salts.

The two types of hardness are permanent hardness and alkalinity. Both types of hardness is referred to as total hardness. Hardness that comes from the composition of carbonate and bicarbonate ions is called alkalinity or temporary hardness. This is termed as temporary hardness because it can be eliminated by boiling the water. On the other hand, permanent hardness cannot be resolved by boiling the water alone because it is the accumulation of sulphates, nitrates, and other hard metals.

Most water supplies have the same hardness and alkalinity levels. Although water hardness and buffering are relative, it should be comprehensible that the hardness is only caused by calcium and magnesium ions while buffering is the product of bicarbonate and carbonate ions. Such similarities are attached to them because both are products of calcium and magnesium carbonates.

The water quality may change from time to time. One good way to oversee if the quality has changed or not both in local water and pond water is to test its hardness. Test kits are designed to measure the water hardness, while ph buffers are used to balance the pH when the water has turned alkaline or acidic. This can help you diagnose the water quality that may affect the fish health.

Different species of fish thrive in various water hardness, so it is important to distinguish the appropriate hardness before starting a fish pond or water garden pond. It is important, though, to use the right types of fish pond supplies. Common pond fish such as as kois and goldfish require moderate to hard water. The maximum hardness for many pond fish is between 100 – 300 mg/litre CaCO3

Why does water hardness mean so much in fish health? This is because the water hardness may affect the osmoregulation. Fish are influenced by the surrounding water. Osmosis or the movement of water molecules can make fresh water fish vulnerable to flooding water, while marine fish suffer from effluence of water.

Fish body has natural regulator against osmosis which is referred to as osmoregulation. The more the fish releases fluids for osmoregulation increases the osmotic effect. Thus, fish diseases are sometime triggered by water hardness when fish can no longer cope with the increased osmoregulation.

How do you modify the water hardness to keep your fish healthy? It is important to regulate the water’s alkalinity regularly for a month to closely monitor the changes in the health of fish. If the alkalinity or general hardness is lower than the optimum level it can be solved by adding oyster of more buffers. If alkalinity is too low, a carbonate buffer will do; while very low general hardness can be resolved by adding calcium or magnesium buffer.