Article 4-5 Odors Are Like a Cup of Black Coffee


By Nicholas Cranley

Hot humid air, containing stale garden odors, needs to be exhausted from a hydroponic environment. The odors are a real nuisance and finding a 100% solution to the odor problem has been attempted by a number of different products with varying degrees of success. Masking agents eliminate the stale odor but leave a recognizable odor in its’ place. Granular activated carbon filters have been very effective in eliminating 100% of the odors, 75% of the time. The odors increase in intensity a week to ten days prior to harvesting and are not entirely eliminated by the filter. Granular activated carbon filters are also bulky in size and weight and need to be strapped to the ceiling to pick up the hot humid air. The heavy humidity and odors fill up the tiny granules of charcoal and in time they must be replaced for a fresh supply, a messy job, usually, once every six months. Activated carbon’s effectiveness diminishes with saturation. There comes a point, without warning when the filter is no longer effective.

This brings us to the most misunderstood and misused of the air deodorizer products, ozone generators. In smaller gardens, utilizing less than 3000 watts of lighting, a small ultra-violet light ozonator can provide not only adequate odor neutralization but also supply a blanket of protection for the plants. UV ozonators will prevent white powdery mildew, spider mites and other airborne pathogens. Even in larger gardens, an ultra-violet ozonator is a necessary component for its dual role. However, in larger gardens, the exhaust systems are too powerful for these low output UV ozonators, and they are not capable of destroying 100% of the odor. A high output corona discharge ozonator must be used inline as part of the exhaust ducting system. Corona discharge ozone can be created electronically or mechanically and the difference is critical to the hydroponic garden application. Only electronic corona discharge ozonators are free from the bimonthly maintenance caused by the build up of nitric acid (a brownish syrupy like liquid) on the ozone producing glass cylinders, used in mechanical corona discharge devices. As the nitric acid deposits build up on these cylinders, ozone production diminishes and stale garden odors continue to be exhausted. After disassembling the ozonator and cleaning the glass tubes with warm soapy water, the ozone level is back to its maximum output. A core and coil, copper wound transformer powers these mechanical ozonators and an ozone output regulator is simply controlling the voltage input to the primary side of the transformer. This means that if the line input is 115 volts 60 herz, one could reduce the line input to 100 volts 60 herz. The secondary output of 4000 volts 60 herz is only marginally effected likewise the ozone output is only marginally effected. An electronic transformer, adjusts the output of the secondary. The electronic ballast typically takes 115 volts 60 herz and transforms it to 4000 volts 30,000 hertz. With total control of the secondary output to either reduce gradually the power to create the corona discharge or to regulate a pulsing effect, the result is that one can control the ozone output arithmetically. This is of significant importance because in the control of odors, you don’t want to displace one foul odor with another recognizable odor. You must produce the same number of ozone molecules as there are odor molecules, then you end up with neutral smelling air exiting the exhaust system.

There is one more crucial component that will facilitate this desirable neutralization in the odor elimination process. This component is a static mixer (baffle box) and it is designed to stir up the molecules of ozone with the molecules of odor. Think of a cup of black coffee. When cream is added to the brew, one sees a white dot on a black background. It’s only when you stir the coffee that you have a real mixture of the two components. Likewise the ozone molecule and the odor molecule are hurtling down the exhaust pipe side by side at 100 mph and may never meet unless forced to.

In summary, the perfect solution to the air problems in a hydroponic environment include, first, a small UV ozonator inside the garden, This is to neutralize odors when the exhaust fan is off and to provide an insurance policy against the potential of airborne pathogens, white powdery mildew and spider mites. Second, the exhaust fan must be fitted with an air filter to prevent a buildup of debris inside a duct mounted, electronic corona discharge ozone generator. An electronic ozonator that is protected from dust and debris is truly maintenance free. Unlike mechanical ozonators, nitric acid does not collect on the ozone producing elements, therefore no disassembling and cleaning every two weeks. Third, immediately down stream from the electronic ozonator, is a static mixer. You can drill a quarter inch hole in the outlet of the static mixer, cover the hole with duct tape and then periodically smell the exhausting air to see if the odor has been neutralized. With an electronic ozonator you can adjust the ozone output to adequately match the increasing number of garden odor molecules. By using this simple sniff test on a regular basis, you can be assured that 100% of the odors have been eliminated. There is no better solution to the 100% solution.