Aquarium Use of Potassium Permanganate

By Frank Cowherd, Michael Barber, and Ben Chou (extracted from PVAS forum thread)

You can buy KMnO4 = potassium permanganate at a lot of local hardware stores. It is sold for the regeneration of green sand towers which remove iron and other minerals from tap or drinking water. I use potassium permanganate to treat my pond when I want to remove algae and pollutants. KMnO4 oxidizes organic materials dissolved in water and turns into a slightly muddy colored suspension. KMnO4 makes a strongly staining purple solution (you can end up with purple fingers) when dissolved in water. If used at the correct dose will not kill fish but at higher doses it will kill fish. It has a lot of uses from improving water quality to treating fish diseases and removing parasites from fish bodies using it as a dip. The literature on treating the large colored carp called KOI recommends strong aeration while using it. And if you use a white tea cup or coffee cup you can monitor the water for active KMnO4 as it will have a pink cast to the water when the background is white. As it is used up it becomes a finely divided, brownish suspended-precipitate of manganese dioxide. The treatment to remove pollutants in a pond include repeated treatments, once per day until the pink color lasts for more than 3 hours. This leaves the pond looking like it has a brown haze or somewhat muddy looking. This can be turned to sparkling clear water by adding hydrogen peroxide. H2O2 is not toxic to fish at a pint per 400 gallons and it converts the Manganese dioxide flocculate into a soluble colorless material. I add about 2 quarts of H2O2 per 4000 gallons. The pond becomes crystal clear in a couple of hours. [Frank Cowherd]


I use potassium permanganate to sterilize nets and keep some mixed up in a seal-able container and dip/rinse after every use. To get it shipped Aquatic Eco Systems had me certify/sign some hazardous materials paperwork and then pay for special shipping. I treat plants for snails and bad stuff with alum and fluke tabs. As you may recall Mike Hellweg was one of our speakers in 2008. He stayed at my place when he visited and while hanging out in the fishroom we got on the subject of treating java moss for the breeding of egg scatterers. He turned me on to a two-day soak in alum and then a final day with a fluke tab for all plants to ensure a pristine environment for the eggs. I have since applied this to all new plants and especially when setting up breeding tanks with plants. I've discovered that much longer than a three day soak (even with lights) the plants start to melt. I have the "recipe" mounted above a couple 5.5g aquariums setup for this purpose. That recipe-page also contains two other treatment regimens. I'll try to bring some copies to the next meeting. [Michael Barber]


Hydrogen Peroxide is used to neutralize PP in the water. I highly suggest you dose by color rather than by amount. The reason behind this is that each of our tanks has a different amount of organics in it. The more organics there is in the tank, the faster the PP will neutralize itself against the organics. So a dirty tank will neutralize the same amount of PP faster than a cleaner tank. So by dosing by amount of volume, you run the risk of either overdosing and burning your fish and killing your biological filtration, or underdosing in which the effectiveness of the PP is negated. If you use too much PP you will either burn your fish or kill them. If your bio is established and you follow my guideline, you will not kill off your beneficial bacteria.


Potassium Permanganate Treatment Guidelines

• Wear Gloves as PP will stain clothing and skin

• Make sure you have not used a dechlorinator in the last 24-48 hours. Dechlorinator will neutralize the effect of PP quickly and reduce its effectiveness.

• Use 32 oz. Gatorade bottle o Mix 4-5 teaspoons of PP powder with 70% full cold tap water. o Shake well to dissolve crystals fully

• Pour 5-10 ML at a time into tank. One capful at a time.

• Turn tank light off to determine color better

• Looking for light pink color to remain for treatment period • Treatment period of 4 hours initially

• Watch for signs of stress – floating,loss of swim control, or going to the top of the tank

• Neutralize with 4-5 capfuls of Hydrogen Peroxide • Complete water change [Ben Chou]

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