Active vs Passive intake.


Auto Warrior
Sep 22, 2017
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Currently Smoking
Fuck knows. The last of my black market bag. Could be anything.
Evening all, Hoping someone can give me some advice on air circulation and temperature control.

So I'm all ready for my first grow. I've done a lot of research (perhaps too much), and I'm ready to go.

My setup;
40x40x120cm premade tent.
300w Viparspectra LED.
6" Extraction fan + carbon filter.
10ltr Airpot.

I'm growing x1 Think Different auto. I plan to LST and maybe scrog, depending on how bold I'm feeling.

Everything is set up, seedling was about a week old before I put it under the light (one set of true leaves).

The issue I'm having though is to do with air flow.
I've got my carbon filter inside the tent, connected to the extractor fan which is in turn connected to some ducting which goes out of the top of the tent.
On the bottom of the tent are three rectangular flaps, when opened they revel fine mesh windows. I assume these are the passive intakes?

The temperature inside floats between 25-27°c, humidity is 50%.

My question is this..
What is the optimal temperature and humidity level for autoflowering strains?
And should I be using an active intake, or will passive suffice? This is something I have been unable to get a concrete answer on. Some people say passive is fine, others say active is essential. I do have a 6" fan inside, to help air flow, but do I really need to be sucking air in?
I've noticed that the sides of the tent are sort of bowed inwards. Like there's a vacuum inside. I assume this will help prevent the smell from escaping, but is this vacuum effect desirable for any other reason?

Any advice much appreciated.
Temps between 22-28oc canna will be pretty happy.
Humidity for veg stage seedling until buds are forming 60-70% is good
For flowering stage around 40% too high in this phase and bud rot can become a problem!
As for passive v active youll never get a straight answer on that one!
Really depends on set up and how your temps are- and where your extracting to. And venting from
Before you begin with lst, maybe think about experience and getting a couple of grows under your "proverbial belt". See how they go first, then do whatever.

25-27 celsius will be just fine. Open one of the larger lower flaps and open a cable flap at top. The bowed in tent is normal. Negative pressure tells you that your fan and filter are working well and are doing the job of working on odor too. For each tent wall I use two bungee cords stretched top to bottom to help with the bowing. The 6" fan should blow over top of plant.

If the extracted tent air is blowing into same room as tent, just make sure you crack a window for fresh air.