“TO REDUCE the risk of recycled water spreading bacteria,
viruses, and other waterborne diseases to crops, it’s important
to disinfect the water before it is recycled through the system.”
1) HEAT PASTEURIZATION
With pasteurization, water is heated and then cooled to
kill bacteria and viruses. Developed in the 1860s, heat
pasteurization is one of the most popular ways to disinfect
hydroponic systems due to its simple design and ability
to terminate the most heat-resistant pathogens. Different
temperatures and contact times are needed depending on the
source of recycled water and what it’s being used for. Due to
potentially high costs of heating and cooling recycled water,
this method is best used by smaller operations.
Benefits
• Water does not need to be pre-filtered.
• Minimal biological and mineral fouling.
Challenges
• Expensive for large operations.
• Over time, high mineral content in the water leads to
the buildup of deposits on the heat exchangers of the
pasteurization system, which will decrease efficiency
and increase maintenance costs.
2) OZONATION
Ozone (O 3 ) is basically just oxygen with three molecules. A
natural gas, ozone is created when the air in the growroom is
bombarded with ultraviolet radiation from the sun. It can also
be created artificially through an ozone production system by
using a high-voltage corona discharge. Ozone is an intense,
thorough, and environmentally friendly way to effectively
destroy bacteria, fungi, and other waterborne diseases. It’s
the strongest available water disinfectant on the market.
Benefits
• Microorganisms can never become resistant to ozone.
• Ozone reacts quickly and has no residual capacity.
• Controlled ozone in the growroom can also
kill spiders and mites.
• Leads to savings on fertilizer.
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Maximum Yield
Challenges
• More expensive to operate than heat pasteurization.
• Ozone is a strong oxidizer and thus highly corrosive.
3) UV DISINFECTION
With this disinfectant method, recycled water is passed
through a radiation chamber that holds one or two high-
pressure UV lamps. In recent years, more growers have
turned to UV radiation as an alternative to chlorination,
largely out of concern for the environment. Ultraviolet
disinfection has a unique effect on microorganisms. It
does not necessarily kill the target but rather alters its
DNA strands so that the microorganism is incapable of
reproducing. A bug that can’t reproduce quickly dies.
Benefits
• UV disinfection is cost-effective.
• If the UV dose is too low, inadequately disinfected water
is automatically returned to the system.
• No toxic chemicals are used, and no byproducts
are left behind.
Challenges
• UV light is only able to remove microorganisms and does
not remove any other contaminants like heavy metals,
salts, chlorine, or man-made contaminants.
• UV light is also only effective if the water being
treated is clear.
While hydroponics is trending upward for both
commercial and hobby growers, it’s important to note that
variables must be strictly controlled to ensure the correct
hydroponic balance is not disturbed once it is achieved.
Without soil as a buffer, any failure in the hydroponic
system can result in rapid plant death. To ensure
maximum quality and yield, no matter what hydroponic
system you use, water samples should be taken regularly
and discussed with a professional.