Hi All,
Ive jut got a bit of query regarding air exchange. If I start by explaining my setup as im not sure if its any good lol.
I use these Inkbird Humidity and Temp controls, they're great especially for controlling humidity, if its too low it kicks the humidifier in, too high, the dehumidifier.
Temperature wise, ive not needed to use anything for heating so that is redundant at the moment however if temperature gets too hot, it kicks the extractor fan on and clears the air out. This is definitely creating negative pressure as I can see the walls of my tent suck in. I then just have a small length of 4" ducting at the bottom, which just lays on the floor and sucks clean air in when the extractor is on. (Hope ive explained that all OK so far).
My query is, if its a milder day like today, temperature may not exceed the value where the extractor kicks in (I have it currently set for 25C with a 2C tolerance so if it goes to 27.1C or above, fan kicks in) If this were to happen and temp not reach 27.1C then effectively theres no air exchange going on in my tent.
How do you guys run your air exchange? Do you have extractor on constantly or do you have a timer of some sort that switches your fan on every now and then? IS the way mine is setup, going to be detrimental to my grow, especially as plants get bigger as natural they'll use more CO2.
If I haven't explained that well, let me know but any advice id really appreciate. Just me being paranoid again and trying to ensure I give the plants the best environment I can lol.
Thanks Everyone.
Temperatures can fluctuate mate, I think having the constant supply of fresh air getting to the plants is preferred over a couple of degrees in temps. Humidity can build up fast when the extractors are off. And then the plants cant breathe.
I only use exhause, i dont use active intake, just passive. And my temps stay reasonable 
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@redeyejedi I run my extraction all the time constantly drawing in fresh air. My inlet duct is the same as you described but i use 2 ducts at the bottom to allow for more air. I run my extraction fan on low unless it cant keep the temps under control.
I bought the ink bird controllers and was thinking about adding a fan to force more air in the inlet if temps get to high and let the controller handle it. Just how i do it im sure others will chime in with their way. best of luck on your grow.
Sativa to change the things I can, Indica to accept the things I can’t.
@twisted1 Thanks mate, I'll do the same as you then and just have my extractor on constantly and then if temp ever does become an issue I'll get a bigger fan which I can add to the cooling control. I took the driver off my light and left that outside the tent and that already seems to have dropped the temp anyway.
I third that.
In my 2x4x5, I run the cheapest 4" Vivosun fan with carbon filter constantly. Passive intake is all you need in a small tent like that IMO- just make sure you leave enough flaps open to draw air in so you don't end up with too much negative pressure like you mentioned. You can cut a ~6" long piece of duct and fit it with a screen in order to increase the intake too if you need. Just make sure it's sealed well so bugs can't crawl in.
And those Inkbirds are AWESOME. I use them for slow-drying my bud in the tent, exactly like you have them set up. Exhaust fan/humidifier combo keeps the tent at a perfect 55%. Legit.
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