With indoor gardening, there are many factors that contribute to grow room odor: heat and humidity, poor air circulation, pollen, plant material, hydroponic growing media, hydroponic nutrient solutions, organic sprays and nutrient additives. This document will help you to understand how you can eliminate bad odor and keep your indoor garden smelling fresh.
Using a carbon filter is a popular method of odor removal and air purification. A good carbon filter is capable of filtering up to 99% of airborne odors. There is no residue smell and no added electrical cost associated with adding a filter to your exhaust system.
How does a carbon filter work?
A carbon filter is used in conjunction with an extractor fan, cleaning the air before it is removed from the grow room. This method helps ensure all stale air is exhausted. The extractor fan draws air through the carbon filter via a pre-filter cover designed to catch any large airborne particles. Air then travels through the screened side walls to the activated carbon. This is where the odor is cleaned and drawn out through the exhaust system.
Installing a carbon filter
Odor rises with warm air. For this reason, we recommend you install your extractor fan and carbon filter at the highest possible position in your grow room.
Hint – Activated Carbon is safe and non-toxic, which means carbon filters can be used in a grow room where cleansed air is recirculated. The use of this ‘scrubber’ should be in addition to your grow filtration system. Scrubbing systems are achieved by attaching a carbon filter to an extractor fan. However, no ducting should be attached to channel the cleaned air outside the grow room. This method continually recirculates the grow room air; reducing dust, fungal spores and odors.
With some particularly bad odor problems, a ventilation system and a separate carbon filter attached to a re-circulation system can be a very effective method of odor control.
It is important to match the correct carbon filter to your extractor fan. For example; a 600 CFM capacity extractor fan needs to be matched with a carbon filter capable of treating 600 CFM of air or more. Do not try to use a lower capacity filter, it may be able to treat the odors but it will significantly reduce the efficiency of the extractor fan, resulting in high grow room temperatures and a short life expectancy for the fan. Likewise, pairing a large carbon filter with a small extractor fan will not result in better odor removal.
Also, for a carbon filter to be effective, the relative humidity of the grow room air must be below 80%.
Popular with many indoor gardeners, ozone generators are very efficient at eradicating bad odors. Ozone also destroys molds and bacteria that can lead to poor plant health and reduced yields. In particular, ozone will help to suppress Botrytis/Flower rot.
How does ozone work?
When ozone gas comes into contact with odor, an oxygen atom splits off from the ozone molecule; oxidizing it into harmless and non-odorous substances. Ozone binds with the odor molecules to neutralize it.
Is ozone safe?
Levels below 0.5 parts per million (ppm) are deemed safe.
Installing an ozone generator
Ozone generators are easy to install, lightweight, compact and have low running costs. There are two types of ozone generators; those that work best for seepage odors that are positioned outside of grow rooms, and those that are designed to work in-line with ducting runs in extraction/ventilation systems.
Non-aerosol air fresheners will help remove unwanted odors, whilst adding a pleasant fragrance to your grow room. However, we would not recommend that you rely on air fresheners as a sole source of odor control - but they are handy when you have to mask an odor!