Potassium Permanganate (PP) — KMnO4
Article by Mick Minns and Dougall Stewart of the UK Discus Club and Association
If you keep discus, sooner or later you are going to hear the phrase 'PP Treatment'. PP is short for Potassium permanganate and it has been used for many years in the treatment of discus, discus water and for the sterilization of aquatic equipment. Frequently PP is used in a quarantine tank as part of the cleaning / debugging protocol for new acquired fish or as a pre-spawning regime for bonded pairs of discus. PP readily oxidises a wide rang of ecto-pathogens e.g. trichodina, costia, white spot, chilodonella, skin flukes and gill flukes etc.
Ok what general information do you need to know about PP.
- Well, it is a very strong oxidizing agent i.e. it will oxidise organic matter, not just the 'nasties' we often find on fish or in water - remember this includes mucus, gill filaments, fins too!
- It is best purchased in powder form (frequently purer than crystals) from a reputable supplier.
- A small 5 or 10g post will treat an awful lot of fish or water.
- PP should always be stored away from sunlight and other chemicals - especially formalin!!!!!
- Apart from its ability to oxidise organic matter it will turn many things it comes into contact with purple!
- Depending on the amount of PP added to pure water it can turn the water from a pale translucent pink to an opaque purple.
- If organics are present in the water, the water will turn a muddy brown as the PP is exhausted.
- It the combination of its oxidising ability and colour change that has made PP treatments so common in the fishkeeping community..
Treating fish
- Lighten the organic load of the tank by giving a large water change with appropriate water.
- When mixing or preparing any chemicals be suitably prepared i.e. wear gloves and eye protection, mix in a well ventilated area away from naked flames etc - it simply isn't worth the risk to cut corners.
- Dose at a maximum recommended dosage of 2ppm aka 2mg/l. Accurate gram scales are a must when using PP - no guessing or using teaspoons please!
- To get the PP into solution you should use a suitable heatproof container. Add the PP powder to the container and pour over it 1 litre of boiling water, stir to make sure the powder is dissolved. Allow the mixture to stand for twenty minutes.
- Slowly add the mixture to the well aerated quarantine tank-preferably into a stream of air bubbles. Once the correct does is added, you should note the deep purple colour of the water, this is a good visual aid to see how quickly the PP is working. In a tank that is light in organics this colour should persist for four hours. If the water turns a muddy brown before the 4 hours is up perform a water 50% water change and wait 24 hours before repeating the procedure. It is better to do this than to keep adding PP in those first 4 hours. The procedure can be repeated a number of times until the purple colour persists for 4 hours. If you suspect that your aquarium/pond has high level of organics you may choose to perform and oxygen demand test1.
- An alternative to monitoring the colour is to employ a calibrated ORP meter. The aim is to keep the level at 450mv for four hours. Do not go above 450mv.
- During the treatment it is important that extra aeration is provided.
Should you need to intervene during the treatment (not all discus react in the same way during oxidative treatments) the process can be halted by the use of sodium thiosulphate (found in most de chlorinators) or by the use of Hydrogen Peroxide (HP) (H2O2). HP is itself a very strong oxidising agent and great care should be taken when neutralizing PP with HP2
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