Carbon Garden Filters
- Remove unwanted odours
- Contains CGV-4 activated carbon
- HIgh quality, great value
- Up to 12 months of constant use
- Pre filter for extra protection
- Available in 4,5 and 6 inch
These high quality Carbon Garden Carbon Filters have been built to the highest quality. They contain CGV-4 activated virgin carbon which will completely eliminate odours on contact. The additional prefilter includes a 0.1 second contact time for the removal of odours. The carbon pellets in this filter are the best available and are made from coconut husks. The layer of carbon pellets is at least 0.4mm thick in every filter.
4″ (100mm Dia) x H:250mm (163m3/h)
5″ (125mm Dia) x H:200mm (160m3/h)
6″(150mm Dia) x H:500mm(480m3/h)
What is a carbon filter?
Carbon filter refers to a method of filtration that uses activated carbon to filter out the impurities of water or air. Carbon filters use a process where the pollutants adhere to the carbon particles as the water or air passes through it. Carbon filters are useful for purifying water and purifying the air of contaminants, but they are also exceptionally useful in removing offending odours from and around indoor gardens. Carbon filtration has been around for hundreds of years and is one of the most common types of water purification systems available. Whether it’s for air or water purification, a carbon filter consists of a lightweight canister that is filled with charcoal or carbon that removes solids and toxins as the water or air moves through it. Carbon filters are handy for gardeners because thy remove chlorine, organic compounds, sediments, and even taste and odour from water, but do not remove the minerals that are valuable to plants. For this reason, carbon filters are common for use in homes, aquariums, garden ponds, and wastewater treatment. When used for air purification, they are simply installed up high in the room’s ventilation system, or they can operate as stand-alone units if that is more convenient. Carbon filtration is also commonly used to remove undesirable water additives or toxins from a hydroponic nutrient solution. Due to their shape, sometimes carbon filters are referred to as can filters, which also happens to be a brand name for a company who manufacturers such equipment. Carbon filters are also used in other types of filtration such as gas masks, some air conditioners, and in odour-proof baggage/luggage.
Exhaust fans and carbon filters are heavy pieces of indoor gardening equipment. Before you purchase a lighter filter, please keep in mind there is a certain amount of active carbon required to adequately filter a given garden space. In other words, there is no way to significantly reduce the amount of carbon, which affects the weight of the filter, without reducing the performance of the filtration system. If a 10-inch by 39-inch filter is required for your garden space, there is little you can do to reduce the weight of the filter. However, there are specific carbon filter stands that would solve your problem with the drywall. Carbon filter stands are sturdy metal stands that can be adjusted to be the desired height within a growroom. Carbon filter stands can be purchased at your local indoor gardening retailer.
Takeaway: Activated carbon filters capture odour-causing vapors and take them out of circulation. Considering using these filters in your growroom? Here’s what you need to know. Activated carbon filters are widely used to reduce odours and control emissions from greenhouses and other growing operations. The ambient air is circulated through the activated carbon filter and returned to the greenhouse or discharged outside. Understanding the basic guidelines of how activated carbon filters work will help growers use the technology with greater reliability and lower overall cost.
How Carbon Filters Work Inside a Grow Room
For starters, activated carbon is basically a sponge that captures odour-causing vapors and takes them out of circulation. The level of odour-causing chemicals is lowered and thus the odour, which is the nose’s detection and quantification of the presence of non-air molecules, is reduced. At some level, called the odour threshold, a typical nose cannot detect the presence of the odour compound in the air and the odour is considered absent, although the chemical is likely still there at a reduced level. This can be a problem, since the slightest increase in the level of the odour compound in the air brings it above the odour threshold and suddenly the odour is detected.
Adsorption vs. Absorption
Activated carbon works by a phenomenon called adsorption, where the odour compound is trapped inside the activated carbon and retained, but the material doing the adsorption does not change size. Adsorption differs from absorption, which also removes things, but the result is swelling. Both adsorption and absorption media have fixed capacities, meaning they hold just so much, since they are storing the material removed from the air, not destroying it. It is easier to tell what is going on with absorption, since the size increase equals the amount of material removed; with absorption, there is a weight gain, but it is hard to measure and we need to use other means to gauge the remaining life of a carbon filter. Activated carbon removes odours by offering the odour-causing compound a more attractive place to reside than circulating in the air. The adsorbed state—when the odour compound leaves the air and gets retained inside the activated carbon—is called a lower-energy state and it is as if the molecule falls into a hole and cannot get out. New activated carbon has lots of unoccupied holes and virtually every compound that passes through falls in a hole and is retained. Over time, the empty holes fill up. The molecules that are adsorbed with higher energy, sort of like weighing more, can displace the lower-energy molecules that are less tightly held, leading to molecular musical chairs. This phenomenon, called displacement, can basically drive one crazy, since odours seem to come out of nowhere when a lightly adsorbed odour compound is knocked off the carbon filter by a heavier compound, whether that compound smells or not. There is no way to program activated carbon to take out one compound and leave the rest alone.
The technical term for the first time an adsorbable compound is sensed at the exit of a carbon filter is called breakthrough and when the filter is full, this is called saturation. When it comes to odours, and especially because of odour fatigue, these benchmarks are in the eye—or nose, I guess—of the beholder.
How Much Can a Carbon Filter Hold?
Activated carbon filters are a bit like oil filters on a car—they remove a certain percentage each time through the filter until they get full, at which point they remove essentially nothing. Depending on the design of the filter, how fast air is passing through it, what is in the air and many other factors, the odour of the exiting air is determined. The end of the filter’s usable life is the point where the amount of odour removed each time through the filter is too little to justify continued operation, at which point the carbon filter should be replaced.
“Ultimately, the capacity in an activated carbon filter is determined by how much carbon there is and the quality of that carbon.“
The amount of odour removed by the filter is the difference between the entering level of odour compound and the level exiting. A lot of removal occurs after breakthrough and after the odour threshold is exceeded. The activated carbon filter continues to remove a portion of the odour compound all the way to saturation.
How Long Do Carbon Filters Last?
Depending on the acceptable level of odour in the greenhouse or exiting air, it may be necessary to take a carbon filter offline well before saturation is reached. Filter manufacturers know this and strive to supply filters that approach the ideal filter performance. The sharper breakthrough and the more vertical the rise, the easier it is to use the entire capacity of the activated carbon filter. In general, the slower the flow rate through the filter, the closer the filter will operate to the limit of ideal performance. Thus, if odour is exiting the filter above the acceptable level, the recommended strategy is to slow the flow rate thorough a filter (using a fan speed controller) to cause the exiting concentration of odour compound to decrease to below the acceptable level. Over the life of the filter, a series of flow reductions will allow the largest total amount of odour to be removed while maintaining an acceptable odour level in the growing space. Ultimately, the capacity in an activated carbon filter is determined by how much carbon there is and the quality of that carbon. It is relatively easy to make an activated carbon filter that looks good right out of the blocks—all the available holes are empty and they grab the first thing they encounter, but the ultimate value of an activated carbon filter is how long it provides ongoing improvement of the air passing through it. Activated carbon quality is like octane in gasoline; you can definitely pack more of it into a given amount of weight or space. Activated carbon quality is determined on a weight basis, per pound of material, through a number of tests, such as iodine number, BET surface area and butane activity. Activated carbons differ in density, or how much weight per unit volume. Thus, one can have a really high capacity (like octane) times a really low density (like popcorn), and one ends up with much less in the tank, so to speak.
Carbon Filter Labels
When selecting an activated carbon filter to purchase, look for quality measurements, which go by names like CTC number, iodine number, butane activity and BET surface area.
Note that different labels use different measures and how much of one equals how little of another is application specific. Truth be told, most of the metrics measure the wrong thing, but it is true that more is better, no matter what is counted.
How Much Carbon Is in the Filter?
The next stop is how much carbon is in the filter: too little of a good thing is, frankly, too little. On the label, carbon may be listed in either weight or volume. If the quality is in units of weight, one must hope that the quantity number is in similar units, or you know nothing.
For example, simply stating that 10 gal. of some number of good stuff per ounce means you are lost if you don’t know the density (ounces per volume). If the calculation has a favorable answer, it will be on the label.
The volume available for activated carbon is how much media the filter will contain, but it is basically the weight of that media that matters. Weight is either how much the filter holds in activated carbon, or the available volume times the density or specific gravity of the carbon.
The specific gravity—the ratio of the weight of a volume of carbon compared to the weight of the same volume of water—is a good indication of quality: the higher the specific gravity, the better.
Good carbons have a specific gravity of 0.45 to 0.55. Specific gravity is easy to measure, just fill a container with the activated carbon, weigh it, then fill the same container with water and weigh that. The ratio of the two weights is the specific gravity.
What Does It All Mean for Growers?
At the end of the day, for a given amount of activated carbon of a given quality, there are few tricks that will make any difference. The flow rate through the filter should be adjusted to provide an acceptable level of odour exiting the filter, and being comfortably below that flow rate is better.
Having more filters is better since they help each other keep the odour level below the acceptable level. Activated carbon does not go bad over time and there is no clever way to use it up faster that leads to increased capacity.