How to Best Filter Your Hydroponic Grow Room
This is a writing sample from Scripted writer Gordon Goodfellow
How to Best Filter Your Hydroponic Grow Room How to best filter your hydroponic grow room depends on several factors which you should take into consideration before you buy any filtering equipment. It will be of help to you if you work out exactly what type of hydroponic system you want to set up (see our beginners' guide at [LINK]) and get a good handle on all the resources that you need in order to set up a grow room which can best handle your needs. We recommend that you read this whole article through once, then start through the various sections of it again as you visualise what you need in your hydroponics system; allow your system to develop in your mind's eye before actually putting it together. Before proceeding let's make it clear that there are two types (and uses) of filters in hydroponics. One is to ensure that the water supply is not contaminated and the other is for the air, to eliminate odours and ensure the growing environment is at its best for the purpose. However, the first type of filter will only be needed in large commercial systems. In small to medium sized hydroponic systems the nutrient-rich water (the nutrient solution) is self-contained, and is stored within the reservoir to be used to irrigate the plants or plant roots, as determined by the type of system you are using. This solution will be replaced at intervals. As the nutrient solution is self-contained and will be replaced altogether at regular intervals, it will have no need of filtering. Therefore, for all practical purposes, the filters discussed here will only be those which clean the air, and not the fluid parts of the growing system. Why You Need Filters in a Hydroponic Grow Room At Caliponics we always recommend that you get a grow tent for your hydroponic system. A grow tent will keep everything in its place and will cater for the provision of the various services you need inside the grow tent such as electricity supply, cooling system, filters and ventilation. How to best filter your hydroponic grow room will inevitably be a product of what is best for your growing environment and your plants. Many grow tents will have compartmentalized interiors for the different components as well as apertures for connecting services in all the right places. So, in this sense, a grow tent will take away many of the problems you'd otherwise be faced with, and supply a lot of the answers in a ready-made solution. Whatever it is that you're growing, you'll need filters to keep the inside air fresh and free from any pollutant substances. This is both to protect the growing environment and to ensure that what goes on inside does not cause irritation or even resentment to other people who live close by. A large part that a grow tent plays is in odour management. Certain plants can be extremely pungent to the extent that they are anti-social. So you will want a way of combining a ventilation and filtering process which deals with this problem first and foremost. That is why you should give this matter a lot of thought before you start buying any other kit. Because the type of filtering and ventilation system you get is determined by the type and size of hydroponic installation you've opted for. We've provided the exact calculations you'll need for working out the type of filter below. Filters which use activated carbon are used to reduce odours coming out of grow tents and grow rooms. This cleans the circulating air, resulting in much fresher air which is free from any spores and odour. It also clears out any allergens (anything which can cause an allergic reaction), pathogens and pollutants. Proper filtering of the air is necessary for people as well, particularly if they're living with respiratory problems and other related health issues. Hydroponic Air Filters Get Rid of Odours How to best filter your hydroponic grow room will be of key concern if you want to get rid of all unwanted odours. Odours from grow tents can be quite intense and sometimes they can be overpowering if you're growing certain kinds of plant. For a variety of reasons, you'll want rid of the smell as much as you can; ideally you should minimise this to zero, and this can be done with the right type of equipment which doesn't need to be expensive. There is also a danger that growers may be so habituated to the smell of their crop that they don't notice it any more. This is more than just getting used to something; the nose's sensitivity actually diminishes if exposure to a specific smell is powerful enough or has been around for long enough. So you may not think that there is any problem at all. Quite apart from neighbours getting irritated or even complaining, you could be at risk from breathing in particles such as mould spores and similar impurities which may be harmful to health. Your awareness of these hazards diminish along with your ability to smell them. Therefore eliminating the smell can quite rightly be said to be healthier as well. The respiratory and associated conditions which can result from this exposure may not present themselves for many years, after which they may stay with the sufferer permanently. Therefore this needs to be addressed right from the start. Air Filters Are Healthier for Plants and People As well as people, plants need fresh air as well. They need fresh, clean air as well as the right temperature and humidity, and the right kind of nutrients and intensity of light. Tiny air-borne particles may be the cause of plant disease, and could possibly ruin your entire harvest. So you need to set up a filtering and ventilation system in order that your plants may breathe freely; all of the recycled air needs to be put through the carbon filter regularly and continuously. ### Grow Room Air Filters For Hydroponics A wide range of different types of air filtering is available. Some of these are very expensive, but you won't actually need the most expensive type for your growing purposes. But the good news is that grow room air filters are among the least expensive types and they're built specifically for the purpose you want. A good grow room air filter will be relatively very efficient and so will not be too heavy a burden on your electricity bill either. ## ## What Exactly Is a Carbon Filter in a Hydroponic System? You can think of a grow room's carbon filter as being similar to a car's exhaust system, in that it removes the impurities (and the smell) and anything remotely toxic or harmful from an enclosed space such as a grow room, a grow tent or a greenhouse. Grow room carbon filters contain layers of activated carbon (a material which is essentially charcoal) with tiny air pores within them. When the air from this enclosed space passes through the filter the smells, dust, pollen and spores are trapped, and because of this your growing environment remains clear of anything nasty. ## How Do Grow Room Carbon Filters Work? So how do these grow room carbon filters work exactly? The carbon filters are sometimes called scrubbing filters; they block any smells from spreading from your growing environment and they trap the particles that you don't want circulating within the carbon components of the filter by what is known as adsorption. That is adsorption and not absorption. Even though the process is similar, adsorption results in an increase in weight and mass of the scrubbing compound. On its journey through the filter, the tiny odour and impurity compounds pass into and through various tiny pores and pockets of air which coat the surface of each layer or bed of activated carbon. They are designed and built extremely efficiently to provide long service (a staggering statistic is that in each gram of this material you'll find several hundred square meters of this internal surface). The impurities are adsorbed in this way by the carbon so that they cannot get out again. All these tiny empty spaces in the carbon beds gradually fill up over a period of time, some compounds displacing other, lighter compounds as time goes on. Eventually, when all the tiny pores are filled up, the filter will have achieved the end of its useful life and will need to be replaced by a new one. As well as standalone carbon filters, you can buy carbon filters with fan or extractor combination units. ## Different Types of Carbon Filters for Your Grow Room The type of carbon filters you need will depend on several things, including the size of your grow tent or grow room (the capacity of air space which needs to be cleaned), the number and size of plants in your hydroponic system and also your budget. So let's consider the different types of filters. #### Carbon Air Filters As previously described, most grow room air filters consist of activated carbon beds which adsorb impurities. The material which comprises the activated carbon is chemically treated and also heated to turn it effectively into charcoal. Each carbon filter contains millions of tiny air pockets or pores which actually attract dust and other impurities. Almost all hydroponic growing methods need this type of filter. #### Non-carbon Air Filters A few other types of filter are available which are non-carbon types. These are sometimes called cabin air filters or particulate cabin air filters. The carbon filters which are generally used in hydroponics are a bit more expensive that the non-carbon variety, but the non-carbon type are also far less efficient. This type of filter removes particles but not odours. So for these purposes you will almost certainly want carbon filters and not non-carbon filters, though they're mentioned briefly here because you need to be aware that these exist so that you don't make the mistake of buying one! #### Carbon Filter/Fan Combination Units In most hydroponic grow systems the best choice will be a filter and fan combination. These, as the name suggests, comprise both filter and fan in the same unit, and their chief advantage is the amount of very necessary work they do relative to the small space they take up. It's also easier to install such units rather than installing two separate devices. With filter-fan combinations, you'll be able to control speed as well, and this is how to best filter your hydroponic grow room with this fan and filter combination. How to Calculate the Size of Your Carbon Filter: The Carbon Filter CFM The size of your carbon filter needs to be worked out properly; you don't want to buy hastily and then be stuck with one the wrong size. The size of a filter is measured by its ability to extract a certain number of cubic feet of air in a given time, and this is given in Cubic Feet per Minute, or CFM. The Capacity of Your Grow Tent Every grow tent or enclosed growing space will have a specific capacity of air which needs to be cleaned and purified, and the size of this will determine the size of your carbon filter. The capacity of the air inside your grow tent or enclosed growing environment is determined by simply multiplying all three dimensions of the tent together (in cubic feet): Volume = Length x Width x Height So, for example, a grow tent which is 10 feet long by 8 feet wide and 7 feet high has a capacity of 10 x 8 x 7 = 560 cubic feet. Extraction of Air Per Minute in CFM You should decide how often you want the air in your grow tent to be renewed, in its entirety, each and every hour. It is generally accepted that smaller grow tents have a shorter renew figure than larger tents, simply based on practicality and cost. So small grow tents can have their air completely renewed about every 60 times per hour, or once per minute, and larger grow tents can have their air completely renewed about every 20 or 30 times per hour, or once every two or three minutes. Taking the example of our 10 x 8 x 7 grow tent above, let's assume that we would like to renew the air inside this grow tent completely every two minutes. We can work this out simply by dividing the capacity of the grow tent by two. So, 560 cubic feet/2 = 280 CFM This means that we'll need a fan which works at the rate of 280 CFM. ### Calculate the Carbon Filter's CFM You may not expect this, but the CFM of the carbon filter will be a bit different from the CFM of the fan. This is because the use of a carbon filter on the fan will impose a resistance (based on the diameter and size, and also the type of connector used) which thus will reduce its working efficiency. The length of the ducting, as well as the material used to make it, will also affect the resistance on your fan's performance. It is thought that, for every 25 feet of ducting which is straight and continuous (i.e. without going round corners), 3% CFM may be lost. This depletion in CFM will be worsened by corners in the ducting, and the angle at which it operates; for example, a right-angle bend in the ducting may account for up to a further 4% loss of efficiency. But as a general rule, an accepted figure to use here is 25%. So we need a fan which is actually 25% better (or higher) when it is used with a filter. This higher figure is called the CFM rating. So the CFM rating of our carbon filter will need to be 280 x 1.25 = 350 CFM. We use this figure when we go shipping for fan units. Whatever the brand or model of the fan we eventually decide on, this figure will remain constant and will be our guide in determining what model we need. ## How to Install a Carbon Filter in the Grow Room There would not be much point in going into great detail about how to install a carbon filter or filter/fan system, as they all differ in some respects, and in each case you should refer to the manufacturer's own installation instructions for that particular system or unit. But there are a few simple things you should remember which are common to most types. The general preference is to install the carbon filters on the inside of the grow tent. Here it can be readily used with the inline fans and ducting, and/or any cooling systems which are in place. If you're really short on space, though, it may be mounted outside. (Some growers may prefer it on the outside for access purposes as well, in some cases.) Firstly, after removing the filter from its packaging, you should fit the pre-filter unit if one is supplied. The filter should then be placed onto the exhaust, and use any rope attachments for hanging if they are supplied and if you need to at this stage. Ensure that, as far as possible, everything that follows the path of the air to be sucked out should be in one straight line and should be unconstricted. Secure everything in place using duct clamps, making sure that all connections are completely airtight ( very important). Test the fan by powering up and looking (and listening) for anything which could be a sign of trouble. Then go along the whole length of the process and make sure that there's no leakage at any stage. In conclusion, this article on how to best filter your hydroponic grow room advises that you get the best carbon filter or filter-fan combination that your budget can stretch to, so that it should last many years, needing only replacement of the carbon filters themselves. If you make sure that the whole system works at the beginning, then that will pay off by rewarding you with many years of good harvests. As time goes by some efficiencies may be improved on the way. See if you can come up with ways of increasing this efficiency, and keep a lookout for new equipment on the market which will improve your system, as technology is constantly changing and developing.
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