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Using Hydrogen Peroxide in Hydroponics: Complete Guide

Using Hydrogen Peroxide in Hydroponics: Complete Guide

Contrary to common belief, hydrogen peroxide has the potential to enhance your hydroponic setup. While it may not be your top preference, it’s worth considering and not disregarding.

How do you use hydrogen peroxide in hydroponics? Hydrogen peroxide is useful in hydroponics in several ways: it purifies water; destroys mold, bacteria, fungi, and algae; raises the oxygen level in the water; helps roots; and stimulates growth in general. Simply mix it into a 3% solution and add it directly into your reservoir.

Read on in our complete guide below and discover everything you need to know about using hydrogen peroxide in hydroponics.

Is Hydrogen Peroxide Safe for Hydroponics?

Hydrogen peroxide is a safe alternative to use in place of harsh chemicals or copious amounts of organic substances for everything from aerating your hydroponic system’s water to clearing up fungi, mold, and harmful bacteria and algae.

You don’t even need to move your plants from the system.

A properly mixed solution of water and 3% hydrogen peroxide simply oxidizes harmful elements in the system, leaving root systems cleaner and healthier.

What Is Hydrogen Peroxide Used for in Hydroponics?

Hydrogen peroxide is used for several significant purposes in hydroponics. A few of the most crucial things hydrogen peroxide does in hydroponics are as follows:

Purifies Water

One of the most important roles that hydrogen peroxide plays in hydroponics is as a potent disinfectant, purifying the water.

When added to the reservoir of a hydroponic system, hydrogen peroxide dissolves into pure water and hydrogen, increasing the available oxygen in the tank and decomposing any pollution in the water.

Kills Bacteria and Fungi

Hydrogen peroxide is on the Centers for Disease Control list of agents that kill bacteria, viruses, mold, spores, fungi, and yeast.

The oxygen molecules created by the hydrogen peroxide oxidize bacteria and fungi just as soon as it hits the water and begins spreading through the system.

Destroys Algae & Mold

Hydrogen peroxide is also known for destroying algae and mold in hydroponic reservoirs and systems.

When the solution hits the water, fresh oxygen is instantly released, and it oxidizes and decomposes algae and mold.

As mentioned above, hydrogen peroxide is known for killing bacteria and fungi in the same fashion as well.

Improves Oxygen Levels

When added to water, hydrogen peroxide dissolves into oxygen and water.

It also cleans most contaminants as well. The overall result is highly improved oxygen levels in the water of your hydroponic growing system.

Increases Plants’ Ability To Absorb Nutrients

Another of the greatest benefits of using hydrogen peroxide in hydroponics is that it makes it easier for your plants to take up nutrients, water, and oxygen.

When the solution mixes into the water of your hydroponic system, it cleans up the bad stuff in the water, including the stuff on your plant’s roots (like algae, mold, and bacteria).

In turn, your plants are able to more easily absorb nutrients.

Boosts Root & Plant Growth

Because hydrogen peroxide increases the oxygen levels in your hydroponic system’s water source as well as cleaning up the unwanted stuff like fungi, algae, and bacteria, it helps boost the overall growth of the entire plant, including its root system.

Great Sanitizer for Entire System

Hydrogen peroxide is one of the greatest sanitizers for entire hydroponic systems because it enters through the water reservoir and cleans up pollutants (including bacteria, mold, spores, and more) as it moves through the hoses, pipes, or other waterways in your growing system.

Improves Germination Rates

Believe it or not, hydrogen peroxide does indeed improve germination rates. All you need to do is soak your seeds in some diluted hydrogen peroxide.

What happens is that the coating on the seeds breaks down faster, becoming softer and allowing more oxygen through.

The end result is that the seeds germinate at a much quicker rate than normal.

What Type of Hydrogen Peroxide Is Best for Hydroponics?

The best hydrogen peroxide to use in hydroponic systems is food-grade H2O2.

The majority of hydrogen peroxide used in hydroponics is the kind that says 35% hydrogen peroxide on the bottle (you’ll find it here), but the more common 3% is fine too. 

If using 35%, the recommendation is 2-3 milliliters of H202 for every gallon of water. If using 3%, add 2-3 teaspoons of H2O2 per gallon of water.

Is Hydrogen Peroxide Antibacterial?

Hydrogen peroxide is indeed an antibacterial agent, antiseptic, or disinfectant. It destroys various types of bacteria and viruses.

It is also used for sterilization applications, as well as a preservative in some cases.

Is Hydrogen Peroxide Antifungal?

Hydrogen peroxide is an antifungal agent according to the Centers for Disease Control. It not only kills fungi but yeasts, viruses, mold spores, and bacteria as well.

When hydrogen peroxide comes in contact with fungi (or other microorganisms), it breaks their essential components down, effectively killing them.

Does Hydrogen Peroxide Damage Plant Roots?

So long as the hydrogen peroxide is properly diluted, it doesn’t hurt plant roots; rather, it does quite the opposite.

Hydrogen peroxide cleans infected areas of plant roots, oxidizing and decomposing fungi, bacteria, viruses, mold, algae, and other microorganisms disturbing the roots.

Can Hydrogen Peroxide Cure Root Rot?

It may not be a magical cure for root rot, but if there are enough healthy roots left to save, yes indeed, hydrogen peroxide may cure your plants’ root rot issue. 

Here’s how you do it: 

  1. Mix 1 part 3% hydrogen peroxide with 2 parts water.
  2. Remove the plant from the hydroponic system, lifting it up.
  3. Snip off the mushy/smelly roots that are beyond saving with sanitized scissors.
  4. Pour the hydrogen peroxide solution over/onto the plant’s roots.
  5. Trim the roots down, leaving only white healthy looking roots.

A lady lifting a hydroponic lettuce plant from the grow tray to inspect the roots.

Can You Mix Hydrogen Peroxide With Plant Nutrients?

It is possible to mix hydrogen peroxide with plant nutrients for hydroponic systems. The best way to do so is simply adding them to the water reservoir together.

The reason for doing so is simple: hydrogen peroxide helps the plants’ root systems absorb more nutrients.

You can mix 3% hydrogen peroxide solutions directly with liquid nutrients or individually into the reservoir at the same time.

How Do You Sterilize Hydroponics With Hydrogen Peroxide?

There are two steps to sterilizing your entire hydroponics system with hydrogen peroxide.

First, introduce a 3% solution to your reservoir, and pump it through your system for 5 to 10 minutes.

Next, mix an additional 3% solution, and use it to physically wipe down all of the components of your system.

You can also change the water and wipe the inside of the reservoir and any components inside (like pumps and filters) as well.

How Much Hydrogen Peroxide Should I Add to My Hydroponic System?

Research indicates that the safest/most beneficial amount of hydrogen peroxide to add to your hydroponic system is a 3% solution.

So, if you are purchasing a 35% hydrogen peroxide product, you may want to dilute it before adding it to your hydroponic system’s reservoir.

How Much Hydrogen Peroxide Per Gallon of Water?

The golden rule is to add 3 teaspoons (approximately 14 milliliters) for each gallon of water present in your hydroponic system’s water reservoir.

For example: If your system is 10 gallons, that’s 30 teaspoons. In a 50-gallon system, you’d need 150 teaspoons, or a 250-milliliter container full.

How Much Hydrogen Peroxide Per Liter of Water?

The recommended amount of hydrogen peroxide to add to one liter of water is a single teaspoon (5 milliliters), though ¾ of a teaspoon (3 milliliters) per liter does the job just as well in smaller systems.

For example, in a 15-liter reservoir, you’d need to add 15 teaspoons or around 74 milliliters of hydrogen peroxide to the water.

How Often To Add Hydrogen Peroxide to a Hydroponic System

Depending on how strong your hydrogen peroxide solution is, the frequency with which you introduce it to your system varies.

Weak solutions may be added as often as daily. If your dosage is stronger, however, adding it to the system every five days to a week or so is recommended.

Precautions When Using Hydrogen Peroxide in Hydroponics

The biggest precautions to keep in mind when using hydrogen peroxide in hydroponics are more for you than your plants:

  • Never handle it without gloves on.
  • Label all of your containers
  • Keep it somewhere your children or pets can’t reach it.

So long as you follow the 3% rule and don’t add it too often, there isn’t much else to worry about!


Hydrogen peroxide is one of the little God-sends that hydroponic gardeners continue to be thankful for each time they use it.

It’s basic but potent, and it makes a world of difference in your hydroponics system.

From keeping algae and fungi in check to killing viruses and bacteria, hydrogen peroxide is truly priceless for use in hydroponics.