Many people have had success with a practical alternative to Malachite Green & Formalin, Potassium Permanganate. Still, it is much more dangerous than Malachite Green & Formalin and is more complicated to use. Potassium Permanganate is an oxidizing agent, which means 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 appropriate starting dose for a very dirty pond will kill the fish in an extremely clean pond. The result you are trying to achieve is having the level of oxidation in the pond high enough for a long enough time to kill the parasites without killing the fish. This is not easy, but it can be done 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 many 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 beneficial 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%. On the other hand, if the pond is brand new and has very little algae growth, you can reduce the dose by 25%.
- Potassium Permanganate is very toxic. Do not breathe it in 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 consumes large quantities of oxygen during the treatment, so make sure the waterfall is running at all times. Add 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 followed by a pink champagne color. As long as the water is a pink champagne color, it is active and is oxidizing any organic matter in the pond, including parasites. When it turns to a yellow tea color, it has been used up and is no longer oxidizing anything. Scoop up a sample of the water in a white ceramic or plastic cup, which will make it much easier to discern 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 a day, then treat the pond one more time with a 20% reduced dose of Potassium Permanganate. 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 clean water. The only exception may be ich. If you suspect ich, you should replace the salt lost during the water change and maintain it for an additional ten days. Do not forget to add a dechlorinator to the new water.
Note: If at any time during the treatment the water gets so cloudy you cannot see your fish and you get concerned, you can neutralize the potassium permanganate and clear up the water by adding Hydrogen Peroxide. However, if you choose to add Hydrogen Peroxide at any time during the treatment, you will need to wait three full days for the Hydrogen Peroxide to evaporate before you restart the treatment.