the power of orp
Now that we know what oxidation is, where does the
reduction element come into play? While oxidizers add
oxygen to other substances, there are reducing agents that
remove oxygen from substances, making the solution more
negatively charged by adding electrons. Examples
of common reducing agents include microorganisms and organic matter such as organic
fertilizers. The standard unit of measure to gauge
the charge of a solution is the millivolt (mV).
The Power of ORP
Many of you may have heard of the term
“killing power” before. This is a slang term
used to define ORP. The killing power
refers to a solution’s ability to, in essence,
kill the micro-organisms inside that solution, causing a higher mV reading and an
increased ORP. Solutions that maintain
a high ORP are considered to have high
killing powers, which translates to a
sterile environment. Drinking water,
for example, should have a high ORP
to reduce potential contaminants that
can be detrimental to human health.
Another common reference
to ORP that circulates in the
industry, is how “dead” or
“alive” your water is. Don’t let
the verbiage in this reference
scare you, however. Dead water is
considered sterile and free of disease, with a low- to non-existent
concentration of bacteria.
Drinking water should also
fall into the category of
dead water, although
it doesn’t sound very
appetizing. Organic
reservoirs contain water often
considered to be
alive, as it provides
a favorable environment for many
micro-organisms and
bacteria to thrive.
Some growers are under
the impression that ORP
doesn’t have much of an impact
in hydroponics, and that it is more
of a concern in swimming pools,
food sterilization and aquariums.
But whether you are growing organically or in a sterile environment, ORP is
influential, and when used correctly, can
contribute to the success of your crops.
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Maximum Yield USA | April 2015
Determining Your ORP Goals in Hydroponics
Oxidation reduction potential describes a solution’s ability
to oxidize the contents that comprise it. When oxidizers are
used, solutions with a high ORP and high mV reading will
result. Solutions with a low or negative mV reading have a
low ORP, and in hydroponics, this might indicate a lot of
organic matter in your solution.
For those of you growing organically or maintaining an aquaponics system, keeping the ORP of your water and nutrient
solution low is recommended. Organic growers intentionally
add beneficial bacteria, such as mycorrhizae, to their nutrient
solutions to help stimulate plant growth. If you find yourself
having to add more beneficial bacteria than you normally
do, consider checking your ORP to make sure the killing
power isn’t too high for your micro-organisms to survive.
For those of you who prefer to grow in a sterile environment, maintaining a higher ORP will ensure best
results. Because hydroponic growing involves a lot of
recirculating water in which organic compounds are
naturally and constantly developing, you will have to
add oxidizing agents regularly to maintain a high
ORP level. One example of a safe and mild oxidizer
with powerful oxidative properties is hypochlorous
acid, which is commonly used in hydroponics to
increase ORP. Unlike hydrogen peroxide,
hypochlorous acid carries few, if any, risks
when it comes to the safety of both you
and your plants. In its dilute form, hypochlorous acid is an Organic Materials
Review Institute-approved chemical,
indicating its safety and effectiveness
in reducing and eliminating the
risk of disease. It is offered for
sale by several brands within the
industry and yields many hydroponic growing benefits, including
increased ORP.
“Whether you
are growing organically
or in a sterile environment,
ORP is influential, and
when used correctly, can
contribute to the success
of your crops.”