Mixing Hydrogen Peroxide: Dilution Solution (h 2 O 2 )

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Organic Answers Column – October 18, 2023 – H2O2 dilution

Mixing Hydrogen Peroxide: Dilution Solution (H2O2)

Here is an updated version of the uses and mixing rates information for using this fascinating tool.

I. Uses for 3% H2O2 (the grocery store and drugstore product)

  • Skin – to kill bacteria in cuts and scrapes – full strength.
  • Drinking water – to kill algae in rain barrels and animal drinking troughs – 8 oz. (1/2 pint) per 50 gallons of water.
  • Fishponds and decorative water features – ½ gallon per 1000 gallons or 1 bottle (16 oz. or 1 pint) per 100 gallons for control of string algae and others.
  • Fish aquariums – 16 gallon tank – 0.1 oz. or 3 ml; 66 gallon tank – 0.4 oz. or 12.5 ml
  • Cleaning hard surfaces – full strength.
  • Earwax – full strength by eye dropper in ears or put on cotton balls.
  • Washing machine and dishwasher – 4 oz. per load.
  • Plant diseases – for disease such as rose rosette, replace 32 oz. (one quart) of water in the Garrett Juice formula with 32 oz. of hydrogen peroxide.
  • Soil improvement – to provide soil flocculation (fluffiness), apply 32 oz. (one quart) per gallon of water. Apply at least 1 gallon of mix to approximately 1000 sq. ft. Doubling the rate would be better.

II. Uses for 27 – 35% H2O2 (hydrogen peroxide or hydrogen dioxide)

  • Swimming pools – for mustard algae, use 1 gallon per 5000 gallons of pool water.
  • Koi and other fish ponds – use 1 cup per 1000 gallons of water.
  • Weed killing – spray weeds with 10% H2O2. See formula below*.
  • Disease control – spray infected plants with a mix of 1 oz. per gallon of water.
  • Soil flocculation – spray soil with a mix of 2 oz. per gallon of water. Apply 1 gallon of mix to approximately 1000 sq. ft.
  • General use – 1 oz. H2O2 per gallon of water when using the 27-30% hydrogen peroxide

It takes approximately 11 times as much water added to 35% hydrogen peroxide to produce 3% hydrogen peroxide. Use 1 oz. of 35% product per 11 oz. of water to make 3% hydrogen peroxide.

Other ways to look at it:

To convert 35% to 3% H2O2

  • 1 part 35% H2O2 + 11 parts of water = 3% H2O2
  • 1 and ¼ cups of 35% H2O2 + 14 and ¾ cups of water = 1 gallon (16 cups) of 3% H2O2.
  • 1:11 ratio of H202 to water = 3% H2O2

**To convert 35% to 10% H2O2
92 oz. of water + 37 oz. of 35% H2O2 = 128 oz. (1gal.) of 10% H2O2.

To convert 35% to 1.6% H2O2
122 oz. water + 6 oz. 35% H2O2 = 1 gal. of 1.6% H2O2.

NOTES: Follow label direction on all hydrogen peroxide products but especially the concentrated products. They can burn skin and injure eyes so handle with great care. The above information is based on a 35% concentration. Some concentrated products are 22- 33% concentrations so adjust your rates as necessary. Do NOT drink 3% hydrogen peroxide or any other mix for that matter! Always pour the hydrogen peroxide to be diluted INTO the water, not the other way around, to avoid a dangerous splash and burn. Wear gloves and eye protection. If you’re not sure about dilutions, this site has a dilution calculator for liquid percentages.