Carbon Filters

Back to Blog

Carbon Filters

Fans & Filters


Carbon filters are an essential part of growing indoors. When used correctly carbon filters can completely eliminate odour in your customers property. Aiding stealth and adding to security. Carbon filters come in many different options, some are great and some are terrible.

There are several factors that really make a difference when it comes to carbon filters. I’ll round down the different factors that can make the difference between a good carbon filter and a bad carbon filter.

#1 Carbon Type

The majority of carbon filters now use Australian mined virgin carbon, it’s ability  to absorb odour has been known for decades and has become the go to choice for hydroponic applications. Only the worst filters use lower grade carbon

#2 Size

The biggest error people make with growing is mismatching the filter to the fan. If you pull too much air through any filter over it’s rated capacity the odour molecules will not be in contact with the carbon long enough to trap the smell. We always recommend oversizing your filter where possible, your customer gets a longer lasting product as a result and isn’t using it at full capacity all the time. Not to mention it’s a great opportunity to up sell!

#3 Humidity

Customer always come back to us and say the filters work great until harvest time. 99% of the time it’s down to high humidity. No carbon filter will work at its optimum rate when the rh is over 80%. We recommend running a dehumidifier whilst you are trimming and monitoring the humidity during drying to ensure it doesn’t go above 55%. For extra safety an ozone generator is guaranteed to destroy any unwanted smells.

#4 Granulated or pelletised carbon

Granulated carbon has a larger surface area then carbon pellets leading to better efficiency.

#5 Packaging technique and transportation

Most carbon filters work great, until they leave the factory and travel thousands of miles across land sea and road before finally being installed. During this time the carbon in some filters can compact leaving voids causing smells to leak through. Our Fox Carbon Filters have a memory foam ring at the top that keeps the carbon in a stable position so even when the inevitable bump occurs it won’t affect the tightly packed carbon and won’t leak any smells.

#6 Carbon bed depth

Filters vary in the depth of the carbon bed, generally speaking the more expensive the filter the deeper the bed of carbon. Unfortunately most companies charge a premium that doesn’t correlate with the amount of extra carbon provided. We recommend oversizing your filter by at least 25%, when you do this you get a lot more carbon contact than a smaller filter with a slightly deeper carbon bed.

#7 Dirty pre filter

Your carbon filter comes into contact with trillions of microscopic dust particles throughout its life span. The pre filter is essential for keeping the carbon clean. When dust enters the filter it clogs the pores in the carbon that are essential for catching the smells. The pre filter should be replaced every 6 months. Our Fox Filters each come with 2 pre filters to ensure you customers get maximum longevity from the carbon.

#8 Inefficient fans

Some fans are designed to pull some to push and some to circulate. Making sure your customer has an appropriate fan is essential. Remember to take ducting length and shape into account when selecting your customers fans.

#9 Smoking in the grow room (gasp!)

Some people just can’t wait, if you smoke around your carbon filter the pores get clogged with tar, plants hate smoke too so keep your grow room smoke free!

Share this post

Back to Blog