Ventilation speed at lights off?

Helmut79

Helmut79

Well-Known Member
How many air exchanges per minute is the minimum ventilation at lights off as long as RH is good?
 
That's 0.33 air exhanges per minute. Sounds WAY far fetched to me. They only need some oxigen at night, doesn't them?

To my understanding 0.2 air exchanges per minute is enough for lights ON.

But lights off must be less, would be my guess.
 
There is a million different answers to this question, I have spent hours on Google throughout my years of growing trying to find the "correct" answer but everyone seems to have their own idea on what correct is.
Helmut79 said:
That's 0.33 air exhanges per minute. Sounds WAY far fetched to me. They only need some oxigen at night, doesn't them?

To my understanding 0.2 air exchanges per minute is enough for lights ON.

But lights off must be less, would be my guess.
Click to expand...
 
Although I don't know the exact amount of air exchange needed at lights off, I do know there are thousands of growers using night and day speed controllers, which they set a temp for lights on and fan runs to keep that temp, in lights off the fan has a minimum idol speed which is considerably slower. Main thing is to make sure your RH doesn't spike too much.
 
A normal home requires .3 APH to provide for proper air quality, but as stated it's kind of subjective to the environment. I change more in the warmer months than colder because I'm cheap and it dries out the space. It also depends on the plant count and growing style. The goal is to keep the air from being over saturated with O2 also and I would think even 1 change per .5 hour would cover that but again it's subjective.
 
Budley Doright said:
The goal is to keep the air from being over saturated with O2 also and I would think even 1 change per .5 hour would cover that but again it's subjective.
Click to expand...
So you're guessing 2 air changes per hour would be enough. That's 0.03 air changes per minute.

That's not much at all. Exactly what I was hoping for.

coreywebster said:
Athere are thousands of growers using night and day speed controller.
Click to expand...
That's exactly my situation. Fan at max speed is 0.2 per minute, which is enough as I'm using CO2. Would be probably enough without CO2 too.
But I want to have the speed control much lower at night to not waste heat.
 
Helmut79 said:
So you're guessing 2 air changes per hour would be enough. That's 0.03 air changes per minute.

That's not much at all. Exactly what I was hoping for.


That's exactly my situation. Fan at max speed is 0.2 per minute, which is enough as I'm using CO2. Would be probably enough without CO2 too.
But I want to have the speed control much lower at night to not waste heat.
Click to expand...

Just replace the room air once or twice a night, if temps/rh allow it.

Are you using a bottle or burner?
 
Helmut79 said:
So you're guessing 2 air changes per hour would be enough. That's 0.03 air changes per minute.

That's not much at all. Exactly what I was hoping for.


That's exactly my situation. Fan at max speed is 0.2 per minute, which is enough as I'm using CO2. Would be probably enough without CO2 too.
But I want to have the speed control much lower at night to not waste heat.
Click to expand...
Well that's probably enough to keep CO2 at ambient but not sure I would vent at all running CO2 but maybe just lower the ppm's at lights out.
 
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