Potassium Permanganate


An effective alternative to Malichite Green & Formalin which many people have had success with is Potassium Permanganate, but it is much more dangerous than Malichite Green & Formalin and is more complicated to use. Potassium Permanganate is an oxidizing agent which means, that to kill the parasites it must first oxidize most, if not all, of the organic material in the pond. For that reason it is hard to recommend a proper dose for a pond unless you know how much organic matter is in the pond. The proper starting dose for a pond that is very dirty will kill the fish in a pond that is extremely clean. The end results that you are trying to achieve is to have the level of oxidation in the pond high enough and for a long enough period of time to kill the parasites, without killing the fish. This is not really easy, but it can be done very successfully if you pay attention to what you are doing. The following is the technique that we have tried and found to be successful:

  • Remove all plants from the pond.
  • Remove as much leaves or debris from the pond bottom as possible.
  • Empty all skimmer baskets.
  • Turn off ultraviolet light.
  • Bypass the biological filter. If you cannot bypass your biological filter, do not use this process. Potassium Permanganate will kill all the good bacteria in your filter, which will cause serious water quality problems.
  • Sunlight tends to break down Potassium Permanganate, so if you can begin the treatment after the direct sunlight is off the pond it can be helpful.
  • The standard initial treatment dose is 1 level teaspoon per 600 gallons of pond water. If the pond is extremely dirty you can increase this dose by 25%. If the pond is brand new and has very little algae growth, you might reduce the dose by 25%.
  • Potassium Permanganate is very toxic. Do not breathe it or get it on your skin.
  • Salt pond to .3%
  • Have some Hydrogen Peroxide on hand in case you need to neutralize it. You can find it in most grocery or drug stores

Potassium Permanganate Treatment Procedure

Potassium permanganate consumes large quantities of oxygen during the treatment so make sure the to the waterfall is running at all times and add some air stones if you suspect the oxygen level may be low. When potassium permanganate is added to the water it will turn the pond a bright purple at first and then a “Pink Champagne”. As long as the water is a “Pink Champagne” color it is active and is oxidizing any organic mater in the pond including parasites. When it turns to a yellow “Tea” color is has been used up and is no longer oxidizing anything. By scooping up a sample of the water in a white ceramic or plastic cup it will makes it much easier to tell when the water changes color.

  • Day 1- Add the proper dose of potassium permanganate to the pond. Note the time it takes to change color. As soon as it changes to a tea color you can stop bypassing the filter.
  • Day 2- Add the proper dose of potassium permanganate to the pond. Note the time it takes to change color. As soon as it changes to a tea color you can stop bypassing the filter.
  • Continue to treat the pond each day until the pond stays pink for at least 8 hours at one time. Skip one day and then treat the pond one more time except reduce the dose of potassium permanganate by 20%. After the pond has stayed pink for the second 8 hour period, neutralize the pond with Hydrogen Peroxide at a rate of approximately one quart for every 2,000 gallons. Within 30 minutes the water should be very clear. Perform a 40% water change and you should have parasite free fish swimming in very clean water. The only exception may be ich. If you suspect ich you should replace the salt lost durring the water change and maintain it for an additional 10 days. Do not forget to add dechlorinator to the new water.

Note: If at anytime during the treatment the water gets so cloudy that you cannot see your fish and you get concerned, you can neutralize the potassium permanganate and make the water clear by adding Hydrogen Peroxide, but if you choose to add Hydrogen Peroxide at anytime during the treatment you will need to wait 3 full days for the Hydrogen Peroxide to evaporate before you restart the treatment.