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How to set up your grow room ventilation

Even as a beginner, you should know how important air flow is for your plants. Stifled, hot air can cause a variety of problems for your plants including disease, stunted growth and pest infestations. On the other hand, clean, and quality air flow allows your plants to absorb the C02 they need for photosynthesis and growth. 

The aim of your ventilation system is to remove the humid air while consistently bringing in new waves of clean air into the grow space. 

And in this guide, we’re going to discuss how to do it.

We’ll share a step-by-step guide to setting up ventilation systems within your grow space, potential reasons your grow room is overheating and a few extra tips for maintaining the optimum temperature.

Why is my indoor grow tent so hot? 

Having a ventilation system set up isn’t the end of the line when it comes to keeping your grow space cool. If not set up properly, your space could still overheat due to transpiration or from the heat emitted from the equipment you’re using. 

Transpiration is the cycle your plant takes while it grows. As the temperature in the space rises, your plants will take more water and nutrients from the soil. This will then move through the plant’s stems, branches and leaves, eventually being transpired back out. The transpired water then evaporates into the atmosphere and increases the humidity in the space. And the cycle starts all over again. 

Grow lights can also contribute to the temperature of your grow space. Bulbs can get incredibly hot and can impact your plant’s ability to grow. 

The good news is, both of these issues can be resolved with the help of proper ventilation. 

What temperature should a growing space be? 

There is a little leeway when it comes to the optimum temperature for your plants. As a general rule of thumb, your plants will thrive in an environment that is between 21-24 degrees Celsius. Even then, it’s only when the room becomes a stuff 29 degrees that serious issues begin to occur. If you’re using a C02 supplementation, these temperatures will vary. 

Do you need an intake fan for a grow tent? 

At Herbal House, we have a simple set of components that we use to create a killer ventilation set up every time. When set up correctly, the system should provide the grow space completely fresh air every three minutes. (Also known as the three-minute air exchange)

Exhaust fans

The first thing you’ll need to move air around and out of the grow space is a fan. We recommend exhaust fans as they are hugely effective in bringing new air in, while also removing the old. All air only passes through the fan once, however, which is why you’ll also need a few other pieces of kit to ensure your ventilation system is as effective as possible. 

What size fan should I use for my grow tent? 

Depending on the size of your grow space, you’ll be able to choose from a variety of fan choices. To ensure you get the best air exchange, you’ll first need to measure how much air needs to be moved and removed from the space per minute. 

To make things easier, you can use the below equation: 

L x W x H 


3 minutes

This figure can then be coordinated with the carbon filter measurements. For example, a 960 cubic feet room would need 320CFM of air removed and a 150-500MM carbon filter to do it. This, in turn, then translates to a 150MM inline fan

When choosing a ventilation fan however, you also need to account for the temperature of the exterior room. If the room is typically stuffy and hot, you’ll need to add an additional 20% to the end CFM figure to mitigate any heat coming from outside the grow space. 

As well as external heat, you also need to equate for the amount of heat your growing equipment is emitting. Grow light LEDs can provide your plants with all the light they need to grow, but will also account for extra heat in the grow space. With this in mind, you should add another 20% to the CFM. The power needed for a carbon could also require you to add an extra 60%. 

Finding the right fan for your grow tent can be incredibly tricky, as the above shows. If you are struggling to understand which fans and filters to use, be sure to contact us and we will walk you through it. 

Not quite sure which size grow tent you should even start with? read our blog on How to choose the right grow tent for some helpful advice.

Carbon Filters

To ensure as much organic compound, odor and pollutant is removed from the air before it exits the grow space, you’ll need to attached a carbon filter. If your grow tent is in a communal area of the house, carbon filters are a great way to keep any smells at bay. The filters on our site are for both commercial and domestic use, with mortuaries, restaurants and growing plants alike all using them to manage odors.

Ducting & Clamps

To attach the filter to your fan, and to hang the ventilation system in the grow space, you’ll need ducting and clamps. 

Ducting is an extendable tube which can be cut to size. It can be attached to one side of the fan and filter to direct air out of the grow space without allowing any to escape. Ducting can be pulled between the grow tent and an open window so that after the air leaves the grow area, it can be removed from the external room, too. 

Clamps are provided with all our ducting packages so that you have everything you need to create a seamless ventilation system in which no air can escape. 

Oscillating fans

If you find your ventilation isn’t working quite as well as you’d hoped, you can use additional oscillating fans to move air around the space and towards the exhaust fan. The oscillating fans can be clipped on anywhere along the grow tent structure. 

It’s also worth mentioning that the grow tents available on our site are all made with the strongest framework which can hold up to 80kg of equipment. There are also ventilation sleeves already in place at the top, bottom and sides of the tents so that you can easily channel ducting through at any point. 

How to set up a grow tent ventilation system? 

There are several ways to set up your ventilation system, and it really depends on your personal preferences. The Elite grow tents sold by Herbal House are the strongest available on the NZ market and can comfortably hold all your equipment – including ventilation – in place. 

The most common ways to set up ventilation is either on the floor of the grow tent, hanging at the top, or just outside the space. 

Whichever set up you prefer, you’ll first need to attach your carbon filter to the exhaust fan, so that odor and pollutants are removed from the air before it leaves the grow tent. You can either connect the two components together directly, or use ducting in between the two as a channel from one to the other. 

When connecting the two directly, secure it in place with a little duct tape to ensure no air can escape. If you’re using ducting, you’ll need to cut a piece to size and secure it with the clamps provided. 

Note: The fan should be attached with the arrow label facing away from the filter. 

Active & passive air intake

Depending on what equipment you have available to you, you can create either a passive or active intake system. 

A passive system brings new air into the space by simply just providing a hole for air to travel through. Using an Elite grow tent, one of the ventilation sleeves provided can be left open with ducting inside to create passive air flow. 

For an active intake system, you’ll need to double up on fans. One will be responsible for pushing air out, which the other draws it in. As heat and humidity rises, it’s always best to set up the removing fan at the top of the grow space, and the other at the bottom. 

Ventilation kits

When buying a ventilation kit from Herbal House, you will receive everything you need for the set up. This includes a fan, carbon filter, ducting and clamps. 

Using ducting 

Each ventilation pack includes a few metres of ducting so that you can plenty to experiment with.

  • If you’re creating a tunnel between the fan and filter, rather than directly connecting the two, you’ll first need to cut the ducting to size. 
  • Stretch it out to just a little longer than the gap between the fan and filter, and slice the ducting with a knife. 
  • Follow the spine of the tubing around. At the bottom, cut the spine wire with side cutters or scissors.
  • You’ll likely find that the ducting doesn’t slip naturally onto the ear of the fan or filter. This is ideal in the long run for ensuring there’s good suction between the two and no chance of air escaping. There should, however, be a little stretch so that you can secure the ducting over the fan and filter to connect the two. 
  • Once in place, wrap one clamp around the end of the ducting and feed it through the lock mechanism to create a loop
  • Pull the end of the clamp to create a tight fit and switch the lock into the locking position. You’ll then need a flathead screwdriver to tighten the lock into place.

Setting up your ventilation on the floor 

If you are stuck for space at the top of your grow space, setting up your ventilation system at the base of your grow tent is a great choice, as it is the most compact set up available. 

You’ll need to stack the fan onto the ear of the filter and seal with tape – just so that no air or pollutants can escape. On the side of the fan, you’ll find an arrow label which should point away from the filter. 

  • Place the fan and filter combo in the corner of the grow space with the fan on top. 
  • Take the newly cut ducting and place it on the top of the fan. 
  • Stretch the ducting to the top of the grow tent and into a ventilation sleeve on the grow tent
  • If you’re using an Eclipse grow tent, the premade sleeves have 2 toggle pulls 
  • Tighten the interior sleeve first to keep the ducting in place 
  • Then double seal the system using the second toggle

How to set up hanging ventilation in a grow tent? 

Those looking to place the fan further up in the grow space can use ducting to create a tunnel between the fan and filter for air to travel through. To hang the ventilation system at the top of the tent, we recommend attaching the filter to one of the outer bars, rather than in the middle. 

  • Loop two straps around the bar. To create the loop, you’ll need to tie the strap at the bottom by threading the strap through the buckle. That way, when we add the filter, you’ll be able to easily tighten the loop to keep it in place.
  • Place the filter into place so that it is balanced on the two loops
  • To add more height, you can tighten the loops at the buckle 
  • To keep the grow space tidy, we recommend then moving the buckles on the straps to the top of the bar so they’re out of the way
  • Then add the fan to the contraption. Ensure the arrow label is pointing away from the filter 
  • Seal the two into place with tape 
  • To support the weight of the fan, move one strap across so that the straps are now supporting both elements. This will help to balance the fan and filter through vibrations and as a result, reduce the noise. 

For this set up, the ducting will be placed at the end of the fan, stretched and directed out of your chosen sleeve at the top of the tent. Make sure to secure the ducting into place with the provided clamps. To ensure all air exits the tent, tighten the sleeve around the ducting using the two toggles. 

Setting up a ventilation system outside the grow tent 

The exterior set up is much easier to set up. The fan is placed above the tent and the ducting travels from the filter, through the top sleeve and to the fan.

For this set up, follow the same instruction as above to hang the filter at the top of the tent. Then, attach ducting to the side and stretch it to attach to the bottom of the fan which is just outside the tent at the top. 

On the other side of the fan, you can then attach a second piece of ducting to direct the air out of a nearby window.

How to improve airflow in a grow tent? 

To get the most out of your ventilation system, you need to ensure good airflow into the tent. 

In order to bring air into the tent, place another length of ducting into one of the duct ports and tighten it into place with the toggles. It’s best to draw air in from the opposite side to which the air is being extracted. 

If you are monitoring the amount of light your plants receive, use a longer piece of ducting so that light can’t travel into the grow tent. 

For additional help with moving the air around the tent, you can use clip-on oscillating fans. 

With this guide, you should have everything you need to create the master of ventilation systems. If you are looking for additional advice, or aren’t sure which products to start with, don’t hesitate to get in touch or read our other article "5 Tips to improve your Grow Room" for some more helpful tips.

Watch our latest video on youtube detailing the best way to set up your new ventilation set up