With a clean, and well maintained grow room with adequate air circulation odour is not generally an issue. Some plants however, especially those with volatile oil such as some herbs, can have a strong odour that can build up in the grow room. This is usually the greatest during the flowering stage.

The Scent of Plants

The smell of a plant may not be such a bad thing, and in fact, is often the part of the plant that is desired such as with roses, lilies, or peppermint. Although you may thoroughly enjoy the scent, it can be a bane to those wishing to grow their crops discreetly.

Lavender, rose, and chamomile, for example, have great scents and are often sold for this purpose alone, but any passersby will be alerted of the grow simply by walking past.

In an indoor grow these smells can become overpowering, and it may be beneficial to reduce this smell for the purposes of the grow. Odour control is also great for keeping your grow discreet and preventing people who are wandering by to remain unsuspecting that there is an indoor hydroponic grow in the area.


There are a few different methods used to control the odour released from a grow room:

1. Scent Masking

This involves covering the scent with another scent to neutralize or cover it. ONA blocks and sprays are a great example of this. They are designed to release their own smell to cover whatever smell your plants are releasing.


2. Scent Elimination

This is the best option for most growers, as it offers a much higher degree of scent elimination than ONA block or similar products.

The best option is using a carbon filter. Also known as a carbon scrubber, they consist of a large cylinder filled with activated carbon to chemically absorb all of the scent causing chemicals in the air. They are designed to be connected to the extraction fan in your grow room to either pull or push the extracted air through them before being released outside the grow room.

Activated carbon has the unique ability of absorbing any of the volatile chemicals that pass through them. Most high-quality carbon filters can filter out roughly 99% of the smell passing through them and last for around a year before needing to be replaced.


3. Ozone Generators

Ozone generators are new to the indoor growing scene. They are designed to combine ozone with the exhaust air which is suggested to neutralize the smell. The problem with these, however, is that they are both bad for the environment and bad for human health. This is a fairly popular option of odour control in some areas of the world, but it not recommended. Carbon filters offer the same or better level of odour control, with much less danger to human health.


Some tips to maximise the odour reduction in the grow room:

1. Keep a negative pressure within the grow room

This can be achieved by having a higher rate of extraction than there is intake. By using a larger extraction fan than intake fan, it will allow there to be more air moving out of the room than in. This creates a negative pressure inside the room and will prevent any unfiltered air from escaping the grow room.

If a positive pressure is present, that is the pressure inside the room is greater than the outside pressure, this unfiltered and scented air will be allowed to escape and release its scent to the world.


2. Seal any leaks or cracks in the grow room

By making sure all air that leaves or enters the room are controlled, by sealing any cracks or holes in the grow room will allow for a higher degree of odour control.


3. Use the right sized carbon filter

If your carbon filter is too small for the amount of air passing through it, the scent will not be filtered effectively. It is even beneficial to opt for a slightly larger filter than is needed. This allows maximum filtration and will prolong the life of your carbon filter.

Also be sure you purchase the correct diameter of venting for the filter. Carbon filters come in a wide variety of sizes. Contact one of our experts today to ensure the right carbon filter is chosen for your system.