Bleach in Hydroponics? Use Cases, Tips, and Alternatives

Bleach is a common household product that has chlorine as an active component which makes it extremely effective against stains, bacteria, fungus, and other microorganisms. Given all its uses, is it safe for hydroponics and how can it be used?

Chlorine bleach can be used for hydroponics to periodically clean the system and treat root rot when diluted and used in proper amounts. It is not recommended to use bleach in a running hydroponics system. It can be used only on an empty hydroponic system with no plants on it.

Bleach is quite the useful product and a better understanding of what you can and can’t do with it will improve your hydroponics garden. There are other alternatives to bleach if you want substances which are more controlled and less corrosive.

Is it Safe For Hydroponics?

Bleach, in controlled amounts, is a safe substance to use in hydroponics. It is widely used by hydroponic growers in making sure that their systems are clean and sterilized after every cycle.

Despite bleach’s reputation as a corrosive substance known to irritate the eyes, skin, and mouth, it is quite a safe substance when used in controlled amounts. Dilution is key here. Diluted bleach is a safe and effective substance for sanitation and sterilization.

The application of bleach for sanitation and sterilization does not only extend to hydroponics and household uses. It is also used for medical purposes and COVID prevention guidelines.

The Use of Bleach in Hydroponics

Bleach primarily has two uses in hydroponics: (1) Sanitization and sterilization; (2) and fighting off root rot. It

Sanitization and Sterilization

The use of bleach in hydroponics is for sterilization and sanitization between growing cycles. A diluted solution of 9.72g/L for powdered bleach and 10ml/L for liquid bleach is recommended for these purposes.

Sanitization and sterilization is necessary because, over time, bacteria, algae, fungi, and other organisms may invade or build up in a hydroponic system. In hydroponics, a controlled system is strived for and the presence of the aforementioned can be detrimental.

The usual procedure consists of removing the plants and then using the bleach solution to scrub the unclean areas of the system. Afterwards, the bleach solution should be run in the system for thirty (30) minutes to one (1) hour.

Treating Root Rot

Due to its strong anti-fungal properties, bleach has proven to be an effective treatment for root rot or other fungal infections. Root rot is caused by overwatered conditions which effectively “drowns” the from absorbing oxygen which it needs for cellular respiration.

4-10 drops of bleach per 1 liter of water (4-10 drps/L) is recommended in treating root rot. The diluted bleach solution is run over the infected root system and made to sit on the solution for 15 minutes.

How to Get Rid of Root Rot with Household Items | Houseplant How-to Ep. 10

Can Bleach Be Used On A Running Hydroponics System?

Bleach cannot be used while there are growing plants in the system. It is not recommended to add bleach in a running hydroponics system because it will kill the growing plants.

Bleach is primarily used for sanitizing and sterilizing after every cycle, creating a clean environment and system for the subsequent cycles. It is not meant to clean the system while the plants therein are still growing.

Is Bleach Environmentally Safe?

Household bleach is environmentally safe due to its high reactivity and instability. Hypochlorite, the anion responsible for the disinfecting and deodorizing properties in bleach, practically disappears upon contact with aquatic environments and has negligible impact on the soil.

Bleach In Hydroponic – Infographic

Bleach in industrial applications do pose some environmental and health concerns because of how they are used in conjunction with other substances which creates toxic byproducts. However, this is not a concern for hydroponic applications.

General Safety Tips with Bleach

Though household bleach is generally a safe and controlled substance, precautions are still necessary when handling and using it.

Wear Gloves, Glasses, and Masks

Safety first! Wear gloves, glasses, and masks because chlorine can cause mild irritation to the skin, lungs, and throat.

This tip is even more important if you have sensitive skin or respiratory complications. Wear protective gear in order to avoid further complications when handling substances.

Do Not Mix Bleach with Ammonia

Bleach should not be mixed with ammonia as it will create chlorine gas. Chlorine gas is toxic. Just for your information, this is the same chlorine gas which was used in chemical warfare in World War I so beware.

There have been reports of mass deaths due to negligent mixing of ammonia and bleach.

Even low levels of exposure at a short duration can cause coughing, wheezing, and irritation to the eyes, nose, throat, and skin. At higher levels, it can cause more severe symptoms such respiratory complications, vomiting, and even death.

Likewise, do not mix bleach with other household chemicals as a general rule.

Different Types of Bleach

Be aware of the type of bleach purchased and read the labels to be informed accordingly. There are three broad classifications of bleach: 1) chlorine based 2) peroxide- based and 3) sulfur dioxide-based.

Chlorine-based bleach wherein the active agent here is chlorine. This is the bleach contemplated in this article and the most common type of bleach.

Peroxide-based bleach wherein the active agent is oxygen. Hydrogen peroxide (H2O2) is also a component here. Likewise, food-grade hydrogen peroxide is used for hydroponics growers in sterilizing and sanitizing their systems.

Sulfur Dioxide-based bleach wherein the active agent is sulfur dioxide.

Alternatives to Bleach

If bleach is not to your liking, there are alternatives which will offer similar results. Hydrogen peroxide, and vinegar can prove as worthy alternatives.

Hydrogen Peroxide

Hydrogen peroxide does all the same things as bleach does but is considered as the safer option. Much like chlorine bleach, it can sanitize and sterilize a system and it can treat root rot.

Unlike bleach, it can be incorporated in the reservoir of a running hydroponic system at a ratio of 3ml/L. This actively prevents root rot and microorganism build up. Food grade hydrogen peroxide (35%) is the best alternative to bleach in sterilizing and sanitizing a hydroponics

Isopropyl Alcohol

Isopropyl alcohol is likewise a good alternative. It can be used to clean and sterilize the surface of a hydroponics system due to its antiseptic, anti-viral, and anti-bacterial properties. However, it is not effective against mold and fungi unlike hydrogen peroxide and bleach.

Isopropyl alcohol should not be directly applied to the plants because alcohol beyond 5% concentration is enough to stunt plant growth. Concentrations higher than 25% will kill the plant. Hence, isopropyl alcohol should only be used to clean an empty system.


1:1 Diluted vinegar is safe for use in disinfecting a hydroponics system. Vinegar has served as a traditional surface disinfectant for centuries. Apart from the smell, it is an effective alternative to bleach and has the benefit of being antifungal as well so it can be used to treat root rot.

Apart from sterilization, sanitation, and root rot treatment, vinegar is also used to adjust the acidity of the reservoir.


  1. Bleach, when diluted properly, is a safe substance in sterilizing and disinfecting an empty hydroponics system. It is used for sanitation and the treatment of root rot or other harmful bacteria, fungus, and pathogens, among others.
  2. It is important to handle bleach with care since it is a corrosive substance. Wear proper safety equipment and do not mix it with ammonia or other substances.
  3. Hydrogen peroxide, alcohol, and vinegar are alternatives to bleach. Hydrogen peroxide can be used on a running hydroponics system unlike bleach. is part of the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites like mine to earn advertising fees by promoting good quality products. I may receive a small commission when you buy through links on my website.


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