Organic Answers column – March 29, 2023 – H202

Mixing Information For Hydrogen Peroxide (H₂O₂)

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

*Always add the peroxide TO the water. Adding water to peroxide can cause dangerous splashing.

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

• Skin – to kill bacteria in cuts and scrapes – full strength. Use once for minor cuts and scrapes.
• 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 – 1 ounce per 16 gallon tank, 1 pint per 66 gallon tank
• Cleaning hard surfaces – full strength.
• Earwax – full strength poured in ears or put on cotton balls.
• Washing machine and dishwasher – 4 oz. per load.
• Plant diseases – for disease such as rose rosette, replace 1 quart of water in the Garrett Juice formula with 1 quart of hydrogen peroxide.
• Soil improvement – to provide soil flocculation (fluffiness), spray and, or drench the soil or tree holes before planting with a 50/50 mixture.

II. Uses for 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 H₂O₂ 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.

Here is a website intended to make these
percent dilution calcuations for you, if you’re
not sure about what you’re doing.

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!

*From Lifehacker:

“Do what you oughta—add acid to water.”‘

Diluting certain acids produces a lot of heat, which makes this deceptively cute lil’ mnemonic incredibly important in a lab setting. Pouring water into concentrated acid generates too much heat way too quickly, which can cause the solution to bubble up or explode; adding the acid to the water instead slows the reaction process down enough that everything stays where it belongs.

The same strategy applies to household chemicals—even those that aren’t acidic at all—but for slightly different reasons. Whenever you pour one liquid into another, there’s usually at least some initial splash back—and if you’re pouring water into a chemical, the displaced liquid flying up at your unprotected eyeballs will mostly be that chemical. (This is even more likely to happen if you crank the tap full blast and stick a mostly-empty container of bleach underneath.) By reversing the order, you ensure the splash back is mostly water, which is significantly less hazardous to exposed skin and mucous membranes.