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The Koi Medic Digital Salinity Tester, now available from Swell UK.
Prevention is better than cure! The maintenance of a balanced salt concentration in the pond is essential for two basic reasons. Firstly, osmosis takes place if there is a difference in salinity between the fish tissues and the pond. Osmosis is the movement of water from less concentrated to a more concentrated solution through a semi-permeable membrane.
Most fish have an internal salt concentration of 1.0% or 10 parts per thousand of salt concentration. This is of a higher salinity than its environment. Thus, water moves from the pond into the fish tissues. This causes the fish to expand its energy trying to get rid of the excess water rather than to fight diseases. However, if the salinity of the water is higher than the fish tissues, then water will be extracted from the fish, causing dehydration.
Secondly, the control of the concentration of salt in the water helps to eliminate harmful parasites that affect the health of your fish. Salt concentration from 0.3% to 0.5% (3 to 5 ppt) upsets the osmosis balance of some parasites. A 0.3% salt concentration is effective at detoxifying nitrites while a 0.25% or higher salt concentration can control the population of string algae.
Floating plants e.g. water hyacinth and water lettuce are effected at lower salinity than bog plants.
Use the Koi Medic tester each time you add salt to the water. Apply dissolved salt in small amounts over several days and use the tester to check the salinity before each application. Do not add huge amounts of undissolved salt directly into the water, this may burn the Koi.
Periodic checks too are important as the salinity of the water is affected in dry or wet weather conditions.
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