Using Salt as a medication in Koi pond

I learnt about using salt to combat against parasites in my Koi pond from the books I bought when I first started by hobby (Koi Kichi by Peter Waddington and Koi Health and Diseases by Dr Erik Johnson). Salt is effective against some parasites so I use it as my “first line of defence” when I suspect there are parasites affecting my Koi. Symptoms are Koi flashing or rubbing themselves on the bottom of the pond or in some cases, visible white spots caused by the Ich parasite). 

I have also used salt as a disinfectant to treat my Koi that was suffering from ulcers and external injuries suffered from knocks against the sides of pond or overhanging rocks. 

Advantage of using salt is that it is relatively cheap, does not kill the bacteria in the filter and somehow helps the Koi to recover faster. There are, however, side effects on some of the water plants. The leaves would turn yellow on prolonged exposure to the salt in the water.

The recommended concentration level is 0.3% salinity. 3 kg of salt for every 1000 kg of water. 1000 kg of water is the weight of 1 cubic metre of water. The Koi Kichi book actually suggests 0.5% for used in a special Koi treatment pond.

For my first and second ponds, which hold 7 tons and 13 tons of water respectively, I need about 21 kg and 39 kg of salt for each treatment. The books recommend to use special salt that are formulated for the pond and aquarium, but I just buy the coarse cooking salt (not the refined table salt) that comes in 3 kg bags from the neighbourhood grocery store. Cheap and good. There are occasions where I have to buy from a few stores as I would practically clear out their entire stock for the week or month, to the store owners’ amazement. They must be wondering what I am doing with all that salt!

I add the salt to my pond over a period of 3 days, starting with 1/3 of the salt on the first day, another 1/3 on the second day and the rest of the salt on the third day. I would normally pour the bags of salt into the first chamber of my filter, and allow the return pump in the last chamber to distribute them into the pond.  By doing so, I hope that the higher initial salt concentration in the filter would kill any parasites or larvae that are lurking in the filter media. Salt does not kill the useful bacteria in the filter, hence the advantage of using salt over other kinds of medication.

I would leave the salt in the pond for about a week or until the ulcers or wounds are healed or symptoms of parasites have disappeared.

How to remove salt? The only way is to remove salt from the pond water is by partial water changes. Unfortunately, this is a slow and gradual process carried out over a period of a few weeks as I would not change more than 20% of my water each time.

Note: Salt may not be able to treat all Koi ailments. For information on other Koi medications and pond treatments and/or to buy online, click here.