Potassium Permanganate KMnO4

This article is a “use at your own risk” proposition. It’s old data and it worked like a charm in its day. Nothing’s changed about Potassium Permanaganate but people may be stupider nowadays, ponds may be different and fish handling might have some tweaks.

Potassium permanganate – by Doc Johnson

Potassium permanganate is one of my favorites in the treatment of Koi, especially in facilities too large for other medicines. This is a big change from 1996 when I suggested folks leave this one alone. It’s a very powerful medicant which can kill fish if not respected.
Potassium is a granular powder which turns the water purple during it’s effect. It oxidizes organic material, including the surfaces of bacterial sores (ulcers) and the parasites that cause them. Once it’s spent it’s energy on the pond and parasites, the potassium turns amber or brown and can be removed with a water change or inactivated with hydrogen peroxide (3% USP) – See peroxide information below.
Potassium permanganate is applied at the rate of one gram per one hundred gallons or one level teaspoonful per six hundred gallons. I use 8 level teaspoonsful in my 4800 gallon pond.
Once the potassium has turned Amber or brown, I can remove it with a waterchange or with Hydrogen Peroxide (3% USP) –
In case of overdosage or untoward reaction to the potassium, you should be aware that it is INSTANTLY de-activated by De-Chlor (Sodium thiosulfate) or also by Hydrogen peroxide. The neutralizing effects may last three to four DAYS afterwards, inhibiting subsequent treatments.
For best results with Flukes, (parasites of trematode class) you would be well advised to treat for several days, but being sure to apply a final treatment on day four or five. This intercepts any emerging trematodes that may have hidden on the bottom.
Ciliates would require daily treatments without water changes in between, to cover about a week period. Please read the other Potassium permanganate articles in this web site or use the information (whole section) in the book. “Koi Health & Disease”