When growing indoors, environment is everything! A successful grower needs to take practical steps to manage factors such as light levels, temperature, relative humidity and CO2 levels. Here we introduce the role of extractor fans and environmental controllers used by indoor gardeners to maintain the ideal indoor environment for their plants.
Why not just go BIG?
Some growers believe the maxim ‘bigger is better’ naturally applies to extraction fans but this is not necessarily the case. Yes, extracting air from your grow room means you’re removing hot air, but you’re also removing humidity at the same time. This means that an over-sized extractor fan can sometimes cause low relative humidity. This, in turn, creates a host of negative effects that will lead to poor plant growth.
Increasing the size of your extraction fans is not always the way to combat heat problems in your grow room. This is especially true in the summer months. (If the air you’re pulling into your garden is already warm then your room will stay warm.) If you can’t keep the heat down and you’re changing the air in your garden more than three times each minute, you need to consider installing air conditioning or using air-cooled grow lights. (See Pro Tools box, right.)
Growers use ducting to channel the air moved by their extraction fans. Insure that all ducting is securely fastened to extraction equipment. The smallest leak (especially those near the extraction fan) can severely reduce efficiency.
It’s also important to plan the “route” from your extraction fan to the outside world / venting area. The shorter and straighter the better. Any bends in your ducting cost you more efficiency reductions. For example, a 30° bend in ducting cuts the amount of air flow by 20%. A 90° bend constricts air flow by as much as 60%!
Oscillating fans (i.e. fans that just circulate the air within the active growing area rather than extract) help to insure that air quality is even throughout your grow room.
Passive vs. Active
When you remove air from your growing area you create “negative pressure.” In other words, you create a “pulling” effect which brings fresh air into your indoor garden to replace the air that’s being extracted. Some growers simply rely on vents and allow fresh air to be passively pulled in through the equalization of air pressure. Other growers use a smaller, secondary fan to actively blow fresh air into the growing space. Smaller input fans are preferred by indoor gardeners as this maintains a slight negative pressure in the growing area which makes your growing environment easier to manage as a whole.