we have all come up against the dreaded green water issue.. this treatment should only be used if you have a good working filtration system with a good UV unit and aeration running..

Using potassium permanganate ( PP ) can and does kill fish.

I am not responsible if you kill your koi.

It is very important that you read and understand exactly what you are doing and understand the risks.

The following treatment will kill algae and dissolve organic matter. It is safe to use with pond plants and fish as long as you follow the directions to the tee.

When using this treatment you should monitor the pond and koi at all times. If you walk away and the koi get in trouble you may come back and find that they are all dead.

The koi will begin to move close to the surface as the treatment progresses, and this is normal. They may occasionally come up to the surface for air, and this is okay. Should the koi start "gasping" at the surface, and remain to the top immediately add hydrogen peroxide ( 3%) at a rate of 6.4 ounces per 1,000 gallons to neutralize the potassium permanganate. (Do not overdose with the peroxide as it is a form of chlorine and could kill your koi) if one koi is doing this it should be okay, but if all of the koi gasping hard at the surface. add the hydrogen peroxide immediately!

Treatment dosage

Before we start it is very important that you Aerate the pond as much as you can. Potassium permanganate can drop the O2 content in a warm pond and this will cause oxygen-stressed koi.. So you must use as much aeration as you can.

MEASURE VERY CAREFULLY. Do not get this in your eyes, or on your skin, as PP (potassium permanganate) is a very strong oxidizer. Add potassium permanganate at the rate of 3.78 grams per 1,000 gallons ( 1ppm ).

once you have added the PP allow the treatment to stand for 1 to 2 hours, with constant aeration. your water should be a pink color and not purple in color. If you have any question about color, fill a clear glass and check the color in the sunlight.

Neutralizing PP treatment

Use hydrogen peroxide ( 3%) at a rate of 6.4 ounces per 1,000 gallons to neutralize the potassium permanganate. when you start to add the hydrogen peroxide the water will start to turn brown almost instantly this is normal, and is a good indicator that the PP is no longer working. when you finish adding the correct amount of hydrogen peroxide it may take a few minutes but the water will clear and the green water will be gone.

As the algae dies the water will turn crystal clear. The dead algae will drop to the bottom of the pond wear it can be picked up by the bottom drain and removed from the pond.

Side notes

always keep hydrogen peroxide ( 3% ) on hand when using PP its a must!!!
hydrogen peroxide also adds a bit of oxygen to the water as well. If a koi starts to crash, remove him to a separate container and add 1 cc of hydrogen peroxide per gallon of water and add an air stone. the koi should rebound in under an hour and can be returned to the pond

i have used this many many times without issue. Again i am not responsible if you happen to kill you koi use at your own risk..

PP Green water treatment rate
3.78 grams per 1,000 gallons ( 1ppm )

Neutralizing PP treatment
use hydrogen peroxide ( 3%) at a rate of 6.4 ounces per 1,000 gallons