This article about ventilating your tent is part of an indoor growing series.
You can catch the rest of FAB’s Indoor Grow Guide at the link below!
Let’s face it: even if you’re keen on growing cannabis indoors, most of us don’t like the idea of our house reeking of the stuff. Even if you don’t care if where you live smells dank as fuck, 24/7… weed is still quite illegal, down under. Discretion is advised.
Adequate ventilation and cooling is a must for any indoor cannabis growing operation. Air circulation and temperature control are crucial for giving your plant its greatest chance of surviving and developing to its highest potential. This could not be more true in the harsh Australian environment.
Keeping the air in your grow tent moving helps protect your plants from mould, bud rot and mildew. Temperature control will prevent your plants safe under strenuous conditions – particularly during the warmer months of the year.
This may sound like a lot… but with the help of a carbon filter and an exhaust fan, it’s actually much easier to solve these problems than one would expect.
Buying Exhaust Fans
Want to give your plants their best shot in life? You’ll need to get fresh air into that tent – and that air needs to circulate.
This is where an exhaust fan comes in handy. You will want to purchase one.
The fan will filter the heat energy produced by your grow light setup.
When it extracts this air, it will go through a carbon filter, which masks 99% of the smell. Your exhaust fan will ideally come with some silver exhaust tubing, to direct the hot air.
If you’re doing a fairly small grow, we recommend a 4” exhaust fan and carbon filter.
You can find the whole kit on E-bay for $107, including the tubing and filter.
This kit is sufficient for tents no bigger than 90cm x 90cm x 180cm. However, if your tent is this size (or bigger), we recommend a 6” exhaust fan.
The 6” fan will give you the option to expand if you so choose to. It also has two speed options – fast and slow. The one we have selected on eBay has ducting, noise reduction clamps, and a carbon filter. It will set you back around $285.
There are fans that exist which integrate ‘smart’ technologies, allowing for variable fan speeds and such. If your tent heats up in the summertime, that extra high-speed setting can help out a lot. The trade off is the noise produced by the exhaust fan. The fans aren’t much louder than a Desktop PC.
To install the carbon filter and exhaust fan in the grow tent, mount it on top of your tent with large zip ties.
For those who opted with non-LED grow lights (eg. MH or HPS lights)… you’ll likely need to run the exhaust through fan through the light to help it cool down. This is why we strongly recommend using an LED light, amongst other reasons!
Which Carbon Filter is Right For You?
Carbon filters trap odours through absorption.
As your exhaust fan pulls in air from the tent, the molecules that produce the odours are trapped in the carbon filter.
Unfortunately, the utility of a carbon filter is finite; these things won’t mask the smell forever. Typically, a large 6” carbon filter will last around 1.5 – 2 years of continuous use. The smaller 4” filters will only last around 1 year.
As soon as you start to notice a smell, it’s a good idea to order yourself a new one from eBay. Typically, the 4” is around $60 and the 6” around $130.
Exhaust Tubing: Where do I Run it?
Ideally, you want your hot air to go out of an open window… or somewhere away from your tent, where the hot air can cool down.
A window is absolutely the best option! You can use a portable air conditioner window adapter kit to help it hold the tubing when out of the window.
Only $34 on eBay! Simply connect the tubing of your exhaust fan, instead.
Air Circulation and Intake are VERY Important!
Moving around the air inside of your tent – as well as bringing in fresh air from outside – will help your plants to grow healthy and strong.
While you must have an exhaust fan, you do not necessarily need an intake fan – that is, unless you’re doing a very large grow!
This is because you can use what is known as the ‘negative pressure’ in the grow tent – where the loose flaps at the bottom of your tent allow for new air to be pulled in slowly by your exhaust fan, which is ventilating out.
Taking advantage of physics makes things cheaper and easier… but, you will still need to find other ways to circulate that air.
We recommend buying 1 or 2 clip-on fans. You can get a 6” clip on grow fan for around $40 on eBay. Hydroponic stores also sell them for around $30-$40. These fans come with a power cable for wall sockets; which is handy, in comparison to other USB-powered options.
If you have a fairly small tent, you could look at the cheaper clip on fans for around $16. For these ones, make sure your power board has some USB ports, or have a USB-power adapter handy.
Do not point these fans directly at your plants. Ideally, you just want to create a light breeze under and above your plants.
How To Monitor Your Grow Tent Temperature
When your plants are in the vegetative stage, you want to keep temperatures around 20-30°C. In the flowering stage, around 18-26°C.
Australia is a hot and humid climate for most of the year. Paying attention to your indoor grow tent’s temperature can be the difference between great success and utter failure.
You can purchase a thermometer with a humidity reader on eBay for $9, which gives you a sensor you can tape to where ever you want in the tent. It also ships with a small digital screen for you to put elsewhere.
Keeping temperatures low is especially important towards the end of the flowering stage (between weeks 6-7) for terpene development. If your temperatures are over 26 degrees Centigrade during the flowering stage, it will slow down bud growth and rob you of all those delicious smells!
Do your best to keep it cool, man!
Keeping Temperatures Down
Keeping the grow tent cool is no easy task in Australia.
Perhaps the best decision you can make to reduce heat inside your tent are some high-quality, heat-efficient LED Lights.
Another way to keep the grow room cool is to turn your lights on at the cooler parts of the day – typically, the night time. If ambient temperatures are lower, your setup doesn’t have to work as hard.
Failing this… your next best bet is to dim the lights a little bit. This can help with the health of your plants significantly… but it will also impact the size of your yield.
The last resort is to use air-conditioning in the room, either through a duct, or a wall system. Additionally, there are more ‘portable’ options, out there. Air conditioning is expensive – know that this option will add to your power bill!
We haven’t mentioned how to warm up your tent, here… because in most regions across Australia, we don’t really expect you to ever need to do this.
If it’s too cold in your tent, just add a heater to the room. Make sure the device stays clear of the plants, for fire safety.
Best of Luck on Your Grow!
That’s about all a beginner needs to know, when it comes to ventilation, cooling and exhausts in your cannabis grow tent.
It’s important to make sure you do this stuff by the book; otherwise, you could be sacrificing optimal yields from your plants. Overheating and a lack of oxygen will result in worse plants. Without an exhaust fan and a carbon filter, you could be at risk of stinking up your whole neighbourhood. Be careful!
Share any questions or advice you may have in the comments; or better yet, contact us!