Ozone is increasingly becoming a go-to resource in hydroponics to battle waterborne and airborne pathogens. While effective, ozone demands expertise and caution. Lacey Macri highlights the benefits and drawbacks of using ozone in the growroom.
In the age of automation, master growers around the world are constantly on the prowl for the next greatest thing to strengthen their game. At the same time, technologists stop at nothing to advance the hydroponic revolution. The unique collaboration of growers, scientists and manufacturers has led to the development of a powerful medley of methods and technology, ultimately leading to a surge in crop production. One such suspect, ozone, has made its way into the growroom and has demonstrated some very substantial, positive effects in a controlled environment.
What is Ozone?
Ozone, or trioxygen, is structurally similar to the well-known oxygen molecule (O2), only a third atom of oxygen is present in the ozone molecule. It is a pale blue gas, and the odor is similar to that of chlorine. It is naturally found in a region called the stratosphere, where the ozone layer absorbs most of the UV light from the sun. The reason so many people always talk about saving the ozone is due to the buffer it provides between ourselves and the sun’s harmful UV rays. Using ozone in hydroponics functions similarly to that of the environment in the sense that it is protecting living organisms by preventing harmful elements from entering the living space.
Ozone in Hydroponics
The most common way ozone is introduced into hydroponics is through an ozone generator. The generators can be thought of as a miniature version of the sun’s UV rays interacting with oxygen to produce the ozone layer. Many ozone generators actually produce ultraviolet light that is reacted with oxygen molecules to do just the same. From there, the ozone is then integrated into the rest of the system, either in the air or in the water, and voila, growers begin to reap its rewards.
Ozone is a multi-faceted molecule with more than one benefit in hydroponics when used properly. Sterilization is its most obvious feature, as it has been used in hospitals, produce packaging and other arenas for decades to reduce the spread of germs and disease. In hydroponics, ozone is capable of vaporizing almost anything in its path. However, consistently running high levels of ozone is not recommended, as it can pose risks to both your health as well as your plants.
The beauty of owning a generator is having the ability to adjust application rates based on your needs. For example, if you are battling an aggressive waterborne pathogen, using an ozone generator that is hooked up to an airstone and placed in the reservoir will completely abolish it at high enough concentrations. While the oxidation-reduction potential (ORP) level of your water rises linearly with the amount of ozone added, the killing power of your solution also increases. Water with high ORP levels above 680 mV has shown to kill pathogens and diseases in the water such as pythium and root rot.
As ozone is produced from an oxygen-fed machine, you can expect increased levels of DO, or dissolved oxygen, to be present. It is crucial to keep an adequate amount of DO content in your water to allow the roots of your plants to breathe. In applications like deep water culture, the roots can suffocate if there isn’t enough oxygen present for respiration. Water with higher DO content has also shown to improve plant health through the increased efficiency of nutrient uptake. At a certain point, the dissolved oxygen content will cease to increase nutrient uptake, however. In other words, there will eventually be a cap on how much nutrients the plants can uptake due to the increased DO levels.
If your issues are airborne, such as molds, mildews and pests, releasing ozone into the air of your growroom will also have strong killing effects. This must be done with adequate expertise and caution, as it can have detrimental effects on the human respiratory system if too much is inhaled. Overuse can also lead to leaf burn and harm to the fruits and flowers of the plants. Some growers even use ozone in the air as a deodorizer.
As you may have deducted so far, ozone can be distributed into the air or water in a hydroponic system. When it is used in the water, the generator is hooked up to an injector system that pulls ozone from the generator and adds it to the feedline as the nutrient solution passes through. When adding ozone directly to your nutrient solution like so, be careful not to overdo it, as it can actually dissolve critical micronutrients like iron and manganese. Damage to the root zone can also occur at high dosages, so it may be necessary to install an air valve to pull fresh air in to mix with the ozone and deliver it to the plants in a more dilute form. Check with the generator’s manufacturer to get professional advice as to what size generator you need, as well as dosing suggestions. Keep your water temperature low to get the best combined results out of your ozone machine.
When releasing ozone into the air of your growroom, be sure to use fans to improve ventilation and prevent ozone from building up in any one area. If you are using ozone to deodorize, it is also suggested to install a carbon filter in the outgoing ventilation ducting to increase the lifespan of the filter as it eliminates the amount of contaminants that will come into contact with it. Additionally, this set-up will reduce the amount of contaminants released from the growroom into the great outdoors, including unwanted odor escape.
While an ozone generator may be on many growers’ wish-lists, the expense may not fit into their budgets right away. The high levels of ORP that ozone facilitates is the mechanism by which sterilization occurs, and there are other products out there that have similar effects. Hypochlorous acid, or HOCl, is a mild oxidizer that also increases ORP and will have increased killing power as the dose increases. Many growers use HOCl to prevent disease, as well as improve the functionality of their equipment through reduced maintenance and the benefits of oxygenated water.