Pond salt is something every fish or koi owner should have on hand at all times. Not only does pond salt help to boost your koi’s natural defence to disease, it reduces the effect of nitrite toxicity, it also adds beneficial electrolytes to the water. But most importantly, when used at the correct dose, it will kill most of the common parasites found in ponds.
Non-iodized salt, Sodium Chloride (NaCl) is the best type of salt to use in ponds with koi and goldfish. It should have no additives, which could adversely affect your fish. Many water softener salts contains YPS (Yellow Prussiate of Soda) which acts as a anti-caking agent. YPS is hazardous to fish. It is inexpensive, safe to use, it will not harm your biological filter, it is useful in treating parasites and helps fight the effects of nitrite toxicity.
It is recommend that you use salt, before you try anything else for parasites because it has so many benefits over other medications.
Most fish have an internal salt concentration of 1.0% or 10 parts-per-thousand (ppt) which is higher than their water environment. Osmosis causes water to transfer from the lower salinity of the pond water into the tissues of the fish. Addition of salt will lower the osmosis pressure. This reduces the effort of the fish in eliminating the excess water. The saved energy is then available for use by the fish’s own immune system to fight diseases.
Salt concentrations between 0.3% and 0.5%(3 to 5ppt) will upset the osmotic balance of some parasites i.e. the parasites’ cells will dehydrate. Salt concentration of 0.3% are effective at detoxifying nitrite and concentration of 0.25% or higher has been used to control some string algae species. Nevertheless, salt can cause pond plant damage as the concentration increases. Floating plants (water hyacinth, water lettuce, etc.) are affected at lower concentrations than most bog plants.
Adding salt in the pond especially in the fall will help fish survive the long cold winter months. We recommend adding 1 – 3 lbs of salt for every 100 gallons of water in the pond. We often add salt in the fall, after taking out floating plants such as water hyacinths and water lettuce.
We carry the KoiMedic Salinity Tester and the Economy Salinity Tester. These pond salinity meters are specially designed to measure the salt concentration in ponds. These meters are accurate and easy to use. All you need to do is turn it on and dip into the pond water.