0.2 air exhausts per 1 minute - how to properly make the calculation?

[Helmut79]

Many of us would agree that a grow room should be ventilated at the rate of 0.2 air exhausts per 1 minute at minimum and 3 air exhausts per 1 minute at maximum, so 0.2 - 3 air exhausts per 1 minute.

Example: Room size is 100 square meters x 2.5 meters of height = 250 cubic meters.

Question: What if only 50% of area is being used for canopy? Lets say plants cover 50 square meters and other 50 square meters is just plain floor.

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1) Would you still need to choose the capacity for the exhaust fan by the size of the whole room, if you want to be exhausting at the minimum rate of 0.2 air exhausts per 1 minute? 250 cubic meters per minute?

2) Or would you choose the capacity for the exhaust fan by % of area that is being used for canopy? 125 cubic meters per minute?

 

[TheYokel]

Whole room.

 

[Helmut79]

Thank you.

 

[Dr. Who]

That's where the enviro controller does the work for you! It runs by temp, RH and (if you spend the big bucks on one) a Co2 ppm controller. I tried one and found that the proper setting of a simple enviro controller to be satisfactory! They turn on the exhaust and shut off when the temps and/or RH is reduced to proper levels, they then turn the gas back on till your set "on time" is reached and turn off the gas. You maintain optimal settings for Co2 use. There are controllers that are set up for Co2 generating devices. Blueprint is a brand that comes to mind for that. They have models that can be cost effective for any wallet size.

 

[TheYokel]

That's where the enviro controller does the work for you! It runs by temp, RH and (if you spend the big bucks on one) a Co2 ppm controller. I tried one and found that the proper setting of a simple enviro controller to be satisfactory! They turn on the exhaust and shut off when the temps and/or RH is reduced to proper levels, they then turn the gas back on till your set "on time" is reached and turn of the gas. You maintain optimal settings for Co2 use. There are controllers that are set up for Co2 generating devices. Blueprint is a brand that comes to mind for that. They have models that can be cost effective for any wallet size.

 

[Dr. Who]

View attachment 3291956

Once he has his exhaust fan for room size. The controller does the on and off work by not a "time" factor, but buy the regulation of the temps and the RH set on the controller.

 

[anzohaze]

That's where the enviro controller does the work for you! It runs by temp, RH and (if you spend the big bucks on one) a Co2 ppm controller. I tried one and found that the proper setting of a simple enviro controller to be satisfactory! They turn on the exhaust and shut off when the temps and/or RH is reduced to proper levels, they then turn the gas back on till your set "on time" is reached and turn off the gas. You maintain optimal settings for Co2 use. There are controllers that are set up for Co2 generating devices. Blueprint is a brand that comes to mind for that. They have models that can be cost effective for any wallet size.

I wish they had a. CO2 Sniffer so ypu dont have to mess with times

 

[Dr. Who]

I wish they had a. CO2 Sniffer so ypu dont have to mess with times

They do. It's costly and I found that the enviro controller works just fine with out it. They make controllers that have them built right in too. Come on,,,you do the math and set the controller. It does what it needs to and can cost from 400 to 700 less then one with a ppm monitor built in. Add on ppm units for Co2 run around 400 each.

 

[Aeroknow]

Yeah. This IS 2014 rite?
I highly recommend buying this, and take all the guess work out(has sniffer also):

http://www.amazon.com/AutoPilot-Greenhouse-Master-Controller/dp/B008SFSI6M

Hopefully you can afford this. Best bang for your buck.

 

[Helmut79]

Once he has his exhaust fan for room size. The controller does the on and off work by not a "time" factor, but buy the regulation of the temps and the RH set on the controller.

Let's forget Co2 enrichment for a second.

1) What if I set the speed of extractor fan at what is required for maximum growth..
2).. and then set the heating device to maintain a required temperature?

If it's freezing outside of the grow room, how else would you control temperature?

Can I be sure the plants are getting enough gas exchange for maximum growth speed (without Co2 enrichment) if I set the fan at 0.5 air changes per minute?

How do I know which extraction rate would be 100% enough for growth?

 

[TheYokel]

If it's freezing outside your tent, are you still able to maintain a constant 85F during lights on and still ventilate adequately?

 

[Helmut79]

Isn't 85F slightly too much when using ventilation?

However, yes to your answer - I'm sure I will be able to add enough extra heat besides lamps and still be able to ventilate adequately. I'm more concerned about the night time when lights are off, but there are many different solutions in terms of heating. Heating devices come in many different forms and sizes. I am just trying to figure out what am I going to need.

By the way, how much fresh air exchange do plants really need at night?

 

[TheYokel]

If you aren't upwards of 80-85F, then why are you worried about pushing so much co2 into the space?

 

[Helmut79]

If you look closer at the first post, I wasn't talking about Co2.

But I'm at the moment in the process of comparing both approaches - ventilation vs Co2 enrichment.

I'm trying to understand which would suit me better in my conditions.

 

[TheYokel]

If you look closer at the first post, I wasn't talking about Co2.

But I'm at the moment in the process of comparing both approaches - ventilation vs Co2 enrichment.

I'm trying to understand which would suit me better in my conditions.

I've looked at all your posts and all your threads. You just seemed to have harvested your first crop last May.

You are going big. I like your room and your plants mainly look healthy other than that CalMag and heat issue you had.

But you still need to get everything dialed in before you start throwing everything you've ever heard of into a room.

You are going 7 directions at once, when you should still be on the road to your first perfect harvest. That's all I am saying.

And don't take any offense to this. Like I said, your plants looked good, I'm just saying my opinion.

 

[Helmut79]

I'm taking it as a compliment. I will probably decide for the favor of another ventilation style grow to improve my results before moving on to Co2 systems.

 

[SnapsProvolone]

A shit ton > than 2 grams per watt can be done in dwc sans co2.

I did a thread somewhere in hydro section where I crudely demonstrated this.

 

[TheYokel]

I'm taking it as a compliment. I will probably decide for the favor of another ventilation style grow to improve my results before moving on to Co2 systems.

It was a compliment

Just stating my opinion of: perfect what you have before you move to a new set-up. I wish every day I could afford and had the room for a room the size of what you ran

Just be sure to dry it slower next time