Information About Ponds and Plants

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This article was first posted on the arborman site March 31, 2001


A Protocol for Using Potassium Permanganate in the Treatment of

Koi and Goldfish

The article below was written by Dr. Roddy M. Conrad who is a koi hobbyist of some renown and also a biochemist. He is a frequent visitor and contributor on a number of koi forums. In brief, it is known that Potassium Permanganate is an oxidizer that clears the water of most of the diseases and organisms that adversely affect Koi.

The recommended treatment has been at 4 PPM, but this dosage can kill fish and many mistakes have been made using PP. The most common problems have been from miscalculations concerning gallons treated or inaccurate measurements of the chemical.

Dr. Conrad has developed a procedure for treating at 2 PPM in concurrent treatments the same day. This makes the use of PP much safer for the fish.

Dr. Conrad can be reached at

1. Introduction

As a koi hobbyist, I have used potassium permanganate treatments of my koi ponds regularly for the past 4 years, and have been pleased with the results. The purpose of this article is to publish the results of the practice for others to consider for their own use. Please do not interpret this article as proposing everyone practice regular potassium permanganate treatments of their ponds. If what you are doing works for you, keep doing it. But if you have some problems, consider the variety of positive effects you will obtain through the preventative maintenance practice of regular potassium permanganate treatments as published in this article.

Please understand that I have treating my ponds with PP down to an exact science, it takes less than 5 minutes of my time during the day to accomplish a full treatment of both ponds. I do not find any reason to "stay by the pond" during this practice. The health of the fish is not in jeopardy if you dose correctly and understand the treatment protocol.

2. My ponds, fish, and general practice

A. Pond and fish description:

I have two hobby koi ponds. One is a 6-year-old outside pond I am presently (March 2000) in the process of rebuilding deeper with more mechanical filtration. This pond is where I developed my potassium permanganate treatment protocol. It has always had a very high fish load. It is irregular shape with an average width of 12 feet, an average length of 20 feet, and an irregular depth of 12 inches to 24 inches, with a very small area in the center at 30 inches depth. I build this pond before I knew much about good koi pond construction, so it is much too shallow, and it is only 1200 gallons of water. It is a "worst case" koi pond construction, in that it is too shallow for good algae control, too shallow for good koi body development, and too little water for the fish load. Its poor design was the reason I started the frequent potassium permanganate treatments, namely to keep the rapid stringy algae growth under control. But after solving the problems that gave such high stringy algae growth rates, I find enough positives of the treatment to keep the practice for my better designed ponds. This outdoor pond has been equipped with a two cubic foot old style bubble bead filter, a 150 square foot surface area cartridge filter, two 40 watt and one 60 watt UV lights for green water control, and two large lava rock trickle tower biological filters. After rebuilding it, it will have a 3 large vortex tanks, followed by a pump, followed by a 4.4 cubic foot Aquadyne bead filter, followed by a 150 square foot cartridge filter, followed by 3 UV lights, followed by 2 large lava rock trickle tower filters.

My indoor pond is an above ground swimming pool set up in the basement of my house. It is a 16 foot diameter round pond filled to 32 inches in depth. The water exits this pond through two 40 inch diameter commercial vortex settling tanks, then goes to a homemade 3 foot wide by 8 foot long tank also filled to 32 inches depth. In this tank is floating 5 net bags containing 25 cubic feet of plastic scrub pads as part of the biological filter. Water exits this homemade tank to two large commercial trickle tower biological filters filled with a variety of biological filter media. The water from one of these trickle tower filters goes through a 40-watt UV light. Above the pond is a 1000-watt metal halide grow light on a moving track to mimic the sun going across the pond. This provides sufficient light to keep some pond plants thriving to absorb nitrate, mostly umbrella palm. Currently all my 55 high class koi which are in the 18 to 27 inches length are in this pond for the West Virginia winter and spring while I rebuild the outside pond to a better design - namely more depth and better mechanical filtration.

I also keep 4 goldfish ponds and 10 aquariums of various sizes with a variety of systems in my home, which I will choose not to describe in this article in the interest of document length. I am a pure hobbyist, with no commercial interests in the koi, goldfish, or pond businesses. I have a pH. D. in chemistry and rocket science (really, no joke), and have worked for a large chemical company inventing new chemical technology on a daily basis for the last 33 years. So you may appreciate that if I have a different idea, I am not a person who is afraid to experiment to find an answer to a set of problems. PP treatment of ponds on a regular basis is something I personally recommend from my technical observations. My wife does psychological therapy for a living, so we make an interesting couple who are unafraid to say and do different things from the general population.

B. Potassium permanganate treatment frequency:

When I have no serious health or water quality problems, I routinely treat my ponds with potassium permanganate every two weeks. When I have serious health problems which appear to be related to parasites, I treat the pond or aquarium twice a week to kill off the parasite population, and do this for at least a month to make sure I killed them all. If I have a significant group of people coming to see my ponds, I treat the pond one to two days before the event with potassium permanganate to make sure the water is sparkling clear and free of any trace of brown color. Our ponds are on frequent display for a variety of events, so usually having them on display causes us to treat with PP on about a two-week average schedule. On occasion, I will go as long as a month during winter months between treatments. I never treat an outdoor pond when there is ice present, since the very cold water stresses the fish enough so I will not consider doing anything further to stress them.

3. Precautions of Using Potassium Permanganate

Before any discussion of potassium permanganate, we need to remember the hazards of handling potassium permanganate.

  • Wear rubber gloves unless you want your hands stained brown.
  • Wear eye protection, especially in any wind, because the tiniest granule in your eyes will give severe pain and is hazardous to vision.
  • Wear old clothes since the stain from permanganate in any clothing is permanent.
  • Do not overdose unless you are trying to kill your fish, I did this the first time I used it for sure, lost half my fish, had estimated pond volume incorrectly.
  • If you dose at around 15 PPM, expect to lose half your fish, and burn the gills pretty badly on those who survive. If the pond is really dirty, you may get by if you dose high since the reaction of the PP with the muck and dissolved organics will drop the level pretty quickly.
  • If you dose an extremely clean pond at 4 PPM, and the 4 PPM dose lasts a long time, you may lose about 5% of your fish to the stress. That is why I dropped my dose to 2 PPM from 4 PPM, at 2 PPM I never get into difficulty.
  • 4. Potassium permanganate treatment protocol

When I dose, I put in between 1.5 to 2.5 PPM of potassium permanganate, and add it slowly, depending on how I am adding it, which depends on the filtration system of my pond. I dropped the dosage to this level after repeatedly getting in trouble with fish stress at the recommended 4 PPM dosage. I am sure about the dosage, since I have confirmed my pond volume four different ways, and can weigh the potassium permanganate dose accurately when I choose to do so. Usually I add one heaping teaspoon per 1000 gallons for the practice of this dose. One heaping teaspoon of PP powder weighs 18 grams. 1000 gallons of water weighs 8,500 pounds. There are 454 grams to a pound, so 1000 gallons of water weighs 8,500 times 454 = 3.9 million grams. 2 PPM for 3.9 million grams would be 8 grams. One heaping teaspoon of the PP powder weighs 8 to 10 grams, depending on how high I heap the teaspoon, so the one heaping teaspoon dose per 1000 gallons is 2.0 to 2.5 PPM dose level.

On the day I dose, it is usually my schedule to do the following:

  • 1. I bypass the biological filter, and I keep the mechanical filter in use. I design my system so this is accomplished in less than a minute. This means turn off pump flows to my trickle tower biological filters, and take the net bags of plastic scrub pads from the tank in my indoor pond outside to lay on the concrete patio in the air while the PP treatment is done on the pond. I usually start the treatment at about 9 AM. I start a good air pump through air stones into the pond to make sure oxygen stays high and mixing stays excellent.
  • 2. I add the first dose; how I add it depends on filtration system of the pond. In my outside pond, I mix it in a bucket and slowly pour it all
  • around the pond, taking probably 10 minutes to accomplish the dose. In my indoor

pond, I have a 800 gallon settling tank into which I just add all the powder all at once since before any fish see the dose it becomes slowly and well mixed. I also keep a large air pump mixing the water in the indoor pond to avoid concentrated spots of PP in the water where the fish live. My indoor pond is a 4000-gallon system currently, set up in an unused room in the basement of our rather large house.

  • 3. I come back in an hour or two to see if the water has any residual pink color. If the pink color is gone, I add the second 2 PPM dose the same way the first one was added.
  • 4. I come back in two to three hours to see whether there is any residual pink, if there is, I wait longer, if there is not and residual pink color, I may add a third dose.
  • 5. After doing this for a few years, I never add more than 3 doses in a given day, because the water gets too brown to tell if there is any residual pink color left.
  • 6. After the pink is gone either the second or third time, I add one pint of 3% hydrogen peroxide per 1000 gallons of water to get rid of the brown manganese dioxide. The peroxide will both oxidize the brown ugly manganese dioxide (the spent form of the permanganate) to a colorless higher oxidation state of the manganese, and it will also react with the active pink permanganate to make non-toxic forms of manganese.
  • 7. I leave the biological filter bypassed until the next morning, that way neither the potassium permanganate nor the hydrogen peroxide will kill the good bacteria. The peroxide can kill the biological filter as fast as the permanganate, but the lifetime of the peroxide is probably only a few hours in a pond environment.
  • 8. I change whatever is required for the specific filter system to use biological filter again the next morning.
  • Many people have asked me whether keeping the biological filters out of service this long kills the bacteria in the filter beds. I see no measurable ammonia or nitrites after a PP treatment, so there is no evidence that leaving my biological filter media out of the water for 20 hours on a regular basis gives any significant reduction in the bacteria population.

All my biological filter media is either in the air, my normal practice, or in 3% salt water, which is my practice when killing a parasite infestation. None of the parasites can live for 20 hours in 3% salt water, and the salt will not harm the bacteria beds. So this is a good way to reduce the time and number of treatments it takes to kill off a parasite population, namely put the biological media in 3% salt water for the duration of the PP treatment of the pond. If I keep the media in 3% salt water, I also put an air stone in this water to keep enough oxygen to maintain the bacteria beds.

5. Positives observed with regular potassium permanganate treatments

The reasons I practice this frequent PP treatment of my ponds:

  • 1. Regularly oxidizing the dissolved organic content of the pond makes the filter system more efficient since the bacteria can concentrate on the ammonia and nitrite, and don’t need to eat up the organic load as well. This has been confirmed at the chemical factory where I work in a variety of different ways on the industrial scale.
  • 2. The PP reacts away the stuff the fish give off in high population densities, which stunts growth. Chris Neaves has posted the information several times on the message board at about the effect and its cause, but left off the PP cure for the problem, I wrote him privately asking him why doesn’t he list the proper cure with the problem.
  • 3. The buildup of manganese stimulates fish growth, the technical literature states that the highest growth rate occurs at 100 PPM manganese levels, and decreases growth at levels of 600 PPM and above.
  • 4. I keep all the parasites killed off by this treatment since PP kills them all, including flukes.
  • 5. I keep all the aeromonas and pseudomonas killed off so no fish can get ulcer disease. I also never use even a spoonful of dirt to pot plants in any of my ponds, only use soil-less potting media made of coconut fiber. When you have dirt, you can never kill out these bugs, since the dirt gives them a place to live and hide from the PP when it is dosed. So I have no dirt, and my water plants still thrive.
  • 6. The combination of PP and peroxide takes the brown tint out of the water (my wife loves clear water with no color, the fish are similar to clouds floating in the sky on a clear day).
  • 7. Regular PP treatment keeps stringy algae killed, which is the original reason I started this practice. My wife hates the appearance of the pond with stringy algae. Now we have enough large koi to keep stringy algae under control by the koi eating it, but when the koi were younger, the buildup of this ugly plant was a serious problem with the pond appearance.
  • 6. Why manganese is important to koi health and growth

A level of 100 PPM of manganese in pond water, or anything up to 100 PPM, has been shown in the technical literature to stimulate higher growth rates in fish! Since my ponds, with the level of treatment I regularly use, and the water exchanges I use, should be running at the 20 to 30 PPM level of manganese, this should stimulate growth rate, in agreement with my observations of my guys growing faster than the normal occurrence.


Levels of manganese at 600 PPM or above in the pond water has been shown to reduce growth rates in fish. That means I am "hitting the sweet spot" as they say in tennis with my levels of manganese to stimulate growth. The stuff Chris Neaves describes on the Koivet message board which the fish give off to retard growth in high population densities will be certainly destroyed by potassium permanganate treatment, another way the permanganate stimulates growth, in addition to the growth stimulation by the presence of the manganese after it has become manganese hydroxide. "C. Ogino and Yang found that the growth rate of koi was affected negatively if the diet is low in manganese and copper." This has led to the better koi foods being formulated with 50 PPM of manganese sulfate content. Below is a frequently quoted statement in documents in internet searches on the effect of manganese on the human body, some of this may apply to fish as well:

Manganese is a mineral that is required in small amounts to manufacture enzymes necessary for the metabolism of proteins and fats. It also supports the immune system, regulates blood sugar levels, and is involved in the production of cellular energy, reproduction, and bone growth. Manganese works with vitamin K to support blood clotting, aids in digestion, and as antioxidant, is a vital component of Sodium Oxide Dismutase, a large molecule that is the body’s main front-line defense against damaging free radicals. Working with the B-complex vitamins, manganese help control the effects of stress while contributing to ones sense of well being. A deficiency in intake of manganese can retard growth, cause seizures, lead to poor bone formation, impair fertility, and cause birth defects. Researchers are also looking at new links between manganese deficiency and skin cancers. While there is no RDA for manganese, the average intake of manganese is between 2 to 9 milligrams per day. Foods high in manganese include avocados, blueberries, nuts and seeds, seaweed, egg yolks, whole grains, legumes, dried peas, and green leafy vegetables. In the material safety data sheet for manganese sulfate, the level of manganese which gives a 50% kill rate of carp in a 96 hour exposure is 2,850 PPM - that’s right, two thousand eight hundred fifty parts per million, or, expressed another way, 0.28 weight % in the water. That gives a huge safety margin of buildup of manganese in our koi ponds before any fish toxicity from manganese is expected to occur. It would take lots of 4 PPM potassium permanganate treatments to reach a toxicity level in the thousands of PPM of manganese. And very little water exchange!

8. Results of PP Treatment

Results of PP treatment in my fish and ponds of my practices; road to the million dollar prize The most important result of my frequent PP pond treatments is that my wife is pleased with the results. I know at least some of the readers can appreciate this statement! My wife did not like the pond hobby until I started the regular PP treatment, because she thought the ponds were not attractive with the stringy algae and brown water. Now the water is always sparkling clear, and we never have a problem with stringy algae. The second important effect is that the practice has allowed extraordinarily good fish health in very crowded fish loads. I have not had a fish get sick unless I introduced new fish since starting this practice 4 years ago, and even when new fish brought back parasites and a variety of other diseases, the PP treatment killed off the parasites, and both antibiotic injections and PP treatments quickly cleared the aeromonas and pseudomonas infections. I currently have introduced no new fish for the last 12 months, and have not had a single health symptom with 55 large koi in crowded conditions for those 12 months. I have not had a fish death in the last 4 years since starting the PP regular treatments. The third important result is unusually high growth rates, and uniformly high growth rates. All my koi grow very fast. The 3 to 4 year olds are all in the 20 to 27 inch length range, and the 2 to 3 year old koi are all in the 15 to 20 inch length range. From my own experience and comparing to other hobbyists, this is unusually high growth rates. If this continues, I may very easily become the first koi hobbyist to grow a gosanke to over one meter in length to claim the million dollar prize for the first one meter long

gosanke in Japan. The fourth important result has been outstanding color in my koi. They are remarkable in the color intensity and pattern, and at least part of this result would appear to be due to the cleanup of the pond by the PP treatment. I do not find better color quality in koi anywhere than in my own ponds.

9. Technical References

a. Potassium and Manganese

I am a chemist, so here is some chemistry for those interested. When permanganate oxidizes organics, it becomes manganese dioxide: KmnO4 plus dissolved organics -… manganese dioxide and carbon dioxide Manganese dioxide is the ugly brown solids you see forming as the reaction occurs. We need to react it away to have nice clear water in the pond again. The specific reactions which occur between hydrogen peroxide and either the active permanganate, or the spent manganese dioxide, are given below for both situations. I will not put the numbers in front of the formulas to make a specific material balance, just indicate what is reacting, what is forming: 6 H2O2 plus KMnO4 plus 8 hydrogen ions ---- Mn(OH)6 plus 4H2O plus potassium ion. This may not be exactly right, but is probably close enough to do a calculation of how much peroxide is need to neutralize a given dose of potassium permanganate. It is the same calculation as for the residual manganese dioxide, as best I can figure, so here goes. hydrogen peroxide reacts with potassium permanganate to give manganese hydroxide plus water (note: the manganese hydroxide probably immediately reacts further to give manganese carbonate or bicarbonate, but that does not concern us here, it is of no practical relevance) 6 H2O2 plus MnO2 plus hydrogen ion ------ Mn(OH)6 plus water hydrogen peroxide reacts with brown, solid manganese dioxide to give of potassium permanganate. This should be a normal "worst case" situation, unless a miscalculation is made and much more is dumped in. If the dose is actually in the 25 to 50 PPM range where the koi are stressed, remember to recommend much more peroxide for neutralization to prevent immediate massive fish death!

Hydrogen peroxide molecular weight is 34.

Potassium permanganate molecular weight is 158.

Assume 1000 gallons of pond water we choose to treat with 2 PPM permanganate three times total before treating it with peroxide. 1000 gallons times 8.5 pounds per gallon times 454 grams per pound gives us 3,859,000 grams of water, or 3.9 million grams of water.

6 PPM potassium permanganate total would be 6 times 3.9 = 24 grams 24 grams of potassium permanganate divided by 158 molecular weight = 0.15 gram moles of potassium permanganate. But we need 6 gram moles of hydrogen peroxide per gram mole of potassium permanganate according to our best analysis of likely reactions, so 0.15 times 6 = .9 gram moles of active

hydrogen peroxide needed. 0.9 gram moles times 34 grams per gram mole = ~30 grams of active hydrogen peroxide needed. But the Walmart stuff most of us have in our homes is only 3% hydrogen peroxide, so 30/.03 = 1000 grams of hydrogen peroxide needed for just the conversion of this level of permanganate and manganese dioxide. This would be 2 pints of hydrogen peroxide needed per 1000 gallons.

b. Hydrogen Peroxide to the System in General

I treat with 1 to 1.5 pints of hydrogen peroxide per 1000 gallons of water following 3 successive 2 PPM treatments, it seems to do the job adequately. Less peroxide has not been satisfactory in my pond use. The calculation above confirms this should occur.


The information posted above was written by Dr. Roddy W. Conrad and is printed with his permission.

Something new May 2013..... I actually used a protocol developed by Roark.  see Roark’s Protocol               3521 Monroe Road           Charlotte, NC 28205
    Telephone 704-618-6214        E-Mail   jack(removethis)