Buying a forced air fan is one of the most underrated parts of a grow box setup. Who thinks that a small fan not only makes the plant stronger but also improves the climate in the box. In this buying guide, I’ll show you what you need to consider when buying and deciding how many fans you need in your grow room.
Choosing how many fans and which type to buy.
Which fan and how many of them you should buy depends on the size of the grow box. Basically, it makes sense to buy several small fans instead of a single larger fan.
Since smaller fans are usually quieter, you can keep the volume of the box low. And if one of the fans breaks down, you still have at least one working ventilator at the start. If you only have one single vent, if you have a defect you are suddenly left without any circulating air.
|Grow Room Fan Requirements|
|Smaller than 2 ft square||1 X ø15cm / 6 inch 5W|
|3 ft X 3 Ft|| 2 X ø15cm / 6 inch 5W |
Blowing at each other
|4 ft X 4 ft|| 3X ø15cm / 6 inch 5W |
2X ø25cm / 10 inch (20W) (on low level)
|5ft X 5 Ft|| 4X ø15cm / 6 inch 5W |
2X ø25cm / 10 inch (20W)
|6-8 ft X 6-8 ft||3x ø25cm / 10 inch (20W)|
|10-16 ft X 10-16 ft||2x swivel Wall mount fan ø40cm 16 inch|
|Larger than 16 Ft||4x FlatFan 50cm 20 inch|
If you want a little more flexibility, you can buy additional center poles for your grow tent. An additional advantage of these poles: The tent will not contract quite as much due to the negative pressure of the exhaust air system. This makes better use of the space in the grow box, as the walls are no longer pulled into the interior.
Why a circulating air fan?
The stalk grows stronger: a light breeze gets the plants moving. This causes the plant to grow the stalk thicker. This stabilizes the plant and forms a solid base for thick flowers.
Temperature and humidity are better distributed: Temperature fluctuations often occur in the grow box. The air is swirled better so that the temperature and humidity in the whole box are better.
The risk of mould is reduced: If the air humidity does go up, mould can quickly develop. The breeze prevents potential water deposits on the plant. This significantly reduces the risk of mould.
A hotspot is avoided: the fan cools the air directly under the lamp so that no hotspot can arise. This means that the upper part of the plant does not dry out as quickly. This allows the plant to better supply the upper flowers with nutrients and water.
Do you prefer one large Fan or several small ones?
We always recommend placing several small fans in the grow box. A single large fan will make a lot of noise. If you prefer to use two or three small ones instead, the end result will be significantly quieter.
Also, with a strong vent in the box, the wind draft will then possibly be too uneven. While a small hurricane is generated directly in front of the fan, only a very small air current may arrive on the opposite side. It is better to have a light but even breeze so that the plants “sway” easily. This is much easier to achieve with several small fans.
You would also be ill-equipped with a single fan if it fails. You then have no more circulating air and you have to wait for the replacement delivery. But if you have several small ones, the failure of one of the devices is not that tragic. The rest can continue to provide wind.
What should you watch out for in operation?
When aligning the clip fan, remember not to point it directly at the plants. It is better to direct the draft just over the tops of the plants.
Alternatively, you can align the fan a little diagonally downwards so that the wind blows directly under the lamp. So you can lower the heat a little directly under the lighting and thus distribute the heat in the box more evenly.
With the oscillating fans, you have to make sure that they only swivel horizontally and not vertically. If the swivel motor is aligned vertically, the service life is considerably reduced. Many growers report broken swing motors on their fans. In most cases, it swivelled vertically, which brought it to its knees after just a few months.
What should you watch out for when deciding how many fans to buy?
Always order from the grow shop: Of course, all kinds of fans that you can find in hardware stores or on Amazon are suitable. But they are not designed for continuous operation. Circulating air fans in grow shops usually have more robust electric motors that are designed for continuous operation.
Not too big: Depending on the grow box, a smaller size may be required. A mini clip fan is sufficient in small grow tents. A standing fan is required for larger grow rooms.
Order a replacement fan: When purchasing, we strongly recommend that you buy an additional fan as a replacement. Should a fan fail, it can be replaced with one immediately. This can prevent potential mould growth