4kg of salt per 1000 liters during health problems. (Maximum 5kg per 1000 liters)
Normal conditions: 2kg/1000 liters.
Start of summer: 3kg/1000 liters.
Salt bath: 1 kg per 45 liters for 10 minutes.
Salt will stimulate a mucus coat to prevent bacteria from attacking the fish and will throw most external parasites off the skin.
It acts as a disinfectant.
It kills 80% of parasites.
It combats the effect of excessive water entering the Koi causing pressure of kidney functions through it's wounds/ulcers(if any).
It lower the toxicity of Nitrite poisoning and should be added when a high Nitrite reading is experienced.
Koi keepers should stay away from chemicals as long as possible and stick to the more natural safest ways of treatment being salt as first treatment.