How to get rid of cannabis smell

Without a doubt, one of the main advantages of growing cannabis indoors is the possibility to control the smell of the plants, which can be truly intense during the bloom stage. For many cannabis aficionados, growing indoors is the only viable way to grow since it is then possible to control and hide the smell of weed. Otherwise, and if you grow outdoors, the smell of your plants will quickly attract the attention of neighbours, robbers and – even worse - police officers.

Next we'll detail some of the most commonly used systems to eliminate the smell of cannabis plants in indoor grow rooms or tents. As you'll see, there is a wide range of possibilities, some of them more efficient than others. Still, and by using the correct system for your growing setup, you'll get rid of the smell of your plants without much trouble, something essential if your want your plants to go unnoticed. Keep in mind that, whatever indoor growing system you're using, light and odour leaks are two major evidence of cannabis cultivation for third parties.

Systems to control and eliminate the smell of cannabis plants

In our article on how to ventilate a grow room we already mentioned some of the most popular ways to manage the smell of cannabis plants. The following are doubtless the most commonly used systems by growers across the world, which have proven their effectiveness in diverse situations, climates, etc. As you'll see, we could split these methods into two groups: those that eliminate or retain odour molecules and those that release intense fragances to mask unwanted smells.

Active carbon filters

In all likelihood, carbon filters are the most popular system among the worldwide community of indoor cannabis growers. Since indoor grows require adequate ventilation and air renewal, and given that using an air extractor is indispensable for that purpose, carbon filters are widely used, for they are passive elements that need an extractor fan to efficiently filter the air.

The idea is simple: the extraction fan directs the air outside the grow space through the air duct. By putting a carbon filter at the beginning or the end of this circuit we'll force the air to pass through the filter, which will eliminate any smell. In some special cases, particularly when growing smelly strains like Cheesy Auto or Lemon OG Candy, double filtering may be necessary: simply put one carbon filter at each end of the air circuit. You can also find on the market special in-line filters designed to be connected to the air duct at any place of the air circuit, which can be used alone or in double filtering setups.

Keep in mind that carbon filters have a limited lifetime. Inside these filters you'll find small carbon pellets with thousands of micro-pores. These pores trap aromatic molecules and remain "occupied" by these particles. These pores can't be "emptied" back to their previous state, o sooner or later (it depends on usage hours and the quality of the material used) it will quickly lose efectiveness. If you grow continuously, this will happen within 18-24 months if you're using quality filters.

Also, note that each filter has a certain capacity - normally expressed in cubic metres per hour or m3/h - which must match the flow capacity of the extractor fan. Normally, the capacity of the filter is slightly higher than that of the extraction fan so the engine of the latter is not overworked. Logically, the effectiveness of this system depends entirely on the continuous operation of the extractor fan. If you turn your ventilation system off, negative pressure inside the growing tent is lost and soon the smell of the plants is obvious outside it.

One last advice: the lifetime of carbon filters is drastically reduced in case of filtering air with more than 75% relative humidity. If this happens, the micropores of the carbon pellets are occupied by both aromatic and water molecules, which quickly decreases their storage capacity. In this way, you should always try to keep humidity inside your growing space below this value.

Ozonizers

Ozonizers are an efficient alternative to carbon filters for removing the smell of cannabis plants, although they require more maintenance by the user and are a bit more expensive. These devices generate ozone gas (O3) through electrical discharges that activate the oxygen present in the air. Besides releasing an extra amount of oxygen to the environment, they eliminate any smell or microbes in the room.

Many people have their grow tent inside a room, or perhaps an entire room is used for growing. In either case, some of them put a carbon filter inside their growing space, connected to the ventilation system, and an ozonizer outside the growing space, inside the room in the first case or anyplace outside the room in the latter. In this way, the air coming out of the growing space is removed by the carbon filter, and any smell leak inside the house is removed by the ozonizer.

You can also find tubular ozonizers, which are connected to the ventilation system in the same way that a carbon filter. Their effectiveness is similar, especially in double filtering setups. Still, they're more expensive than carbon filters and require maintenance, which explains why the vast majority of growers choose carbon filters rather than tubular ozonizers.

Anti-odour gels and blocks, essential oils and others

Another option to control the smell of our plants is to use anti-odour gels or blocks. They're usually placed at any point of the ventilation circuit by using dispensers that are easily connected to the ducting. While not as effective as the aforementioned systems, especially if you're growing particularly smelly strains, they are a very useful option to eliminate the odour of this type of strains during the growth stage, that is to say, when keeping mother plants and cuttings.

Besides these systems - which are the most commonly used - we can also find a wide range of alternative options. These are normally more affordable than the mentioned methods, although of course not as efficient as carbon filters or ozonizers: essential oils, anti-odour tablets, air fresheners, etc. Still, and while these systems may not be suitable for eliminating the smell of live plants in full bloom, they can be useful to keep the house where you grow or smoke with a pleasant scent, especially if you're not using a vaporizer.

As you can see, the number of different options to control and eliminate the smell of your cannabis plants is large. Once again, we strongly recommend to use these systems in order to keep your grow discreet and safe. Growing marijuana without any smell control system can be extremely risky, it is doubtless the best way to let everyone know what you're doing.

Happy harvests!