passive or forced air intake with CO2???

[darrinjefferson]

howdy everyone!
so I am about to start building my new grow room and I have still to answer the most key piece of the puzzle.

Should I use a passive intake or use a fan to blow air in?

I am using CO2 so I know everyone says the room needs to be sealed. The lights will be running on their own air line and then I will have a fan exhausting the room. The exhaust fan will be turned off obviously when the CO2 is on to avoid pulling it out. I just dont know if it matters if I use passive or forced air intake.

In my mind I dont see much of a problem using the passive intake.

If anyone can give me their thoughts I would appreciate it. Anyone with some experience??

Thanks everyone
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[hoosierdaddy]

darrin, I don't have any experience with Co2 systems, but I can tell you that whether you are on a passive or positive flow air system, you should be at a neutral situation when the Co2 is being administered. So, it really shouldn't matter what sort of air flow system you have, when it comes to the Co2.

Now, for other reasons, such as odor control, the passive flow air system is by far superior. Positively blowing air into the grow could allow odor to escape the slight gaps that may exist, whereas the passive won't allow this to happen.

I am sure one exists, but I have yet to personally see a grow situation that would benefit from having a positive/forced air flow.

 

[darrinjefferson]

thanks hoosierdaddy! That is exactly what I was thinking. I wanted to put one or two passive intakes and use a 8" vortex with a carbon filter to exhaust the room. There will be 2 16" x 20" vents in the wall. Thanks for the advice.
If I use passive would one larger vent or two smaller one be better? Personally I think that two smaller ones would do just fine and then I could space them out so more fresh air throughout the room.

any thoughts anyone??


Anyone else have experience with this?? I would appreciate any extra help!!

Thanks

 

[hoosierdaddy]

An 8" duct is 50.25 sq inches of area.
It is always a good idea to have your air intake approx twice the size of your exhaust.
Although a 16" x 20" vent cover is 320 sq inches, you can count on the air flow area being a little less than half of the vent size.
One of those will probably do the trick with the 8" exhaust.

 

[darrinjefferson]

hmm that is interesting. so you think I could get away with a vent smaller than
16" x 20" huh?
So theoretically I could use a 9" x 12" at 108sq inches and I should be fine?
Just seems like a small opening for the size of the room.
The room is 8' x 8'. maybe I am just being dumb.
Thanks again hoosier for your help with this.

Again anyone else that thinks they can help feel free!!
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[smokadepep]

just got 2 burners in an awesome deal, now i want to include it into the setup im putting together, i am not too sure how to set it up, i have two jardin dr150s tents, they both have a 1k hps which is aircooled and sealed from the room, now for the burner, should i let it sit on the floor, or hang it from the top poles of the tent? also what should my intake and outtake be like? do i run the fan and then when it shuts off, run the co2 ,and how often for both?

 

[darrinjefferson]

just got 2 burners in an awesome deal, now i want to include it into the setup im putting together, i am not too sure how to set it up, i have two jardin dr150s tents, they both have a 1k hps which is aircooled and sealed from the room, now for the burner, should i let it sit on the floor, or hang it from the top poles of the tent? also what should my intake and outtake be like? do i run the fan and then when it shuts off, run the co2 ,and how often for both?

The search bar is great for this stuff. you can look and see other peoples setups. your question might get answered if ya start your own thread too, instead of thread jacking mine.

 

[hoosierdaddy]

OK, I stated that you can count on the air flow being less than half of the vent size.
So, no...theoretically or in reality, the smaller sized vent is going to be too small.

Although Ms Nature tells us that mass of air flow at entrance is equal to mass of air flow at exit, it helps for us to keep our intakes larger than our exhausts...or at least what we may perceive as being larger.
A 9" x 12" opening is 108 sq inches, but we are talking a vent here, not a raw opening.
The metal that makes up the vents is blocking more than half of the space.

 

[darrinjefferson]

ok I see what your saying. so my original plan of using a couple vents, perhaps
2- 9" x 12" vents. I will probably do something right around that. Possible a bit bigger even. Just to make sure I have enough.

I had an idea. If I used 2 vents but had them much larger I could sandwhich an air filter in the middle to filter the air.

thanks hoosier for the help

 

[G33k Speak]

If you have CO2- why would you want to vent the room??

Just seal the room and inject the CO2- al you need to remove is the heat.

Use a sealed reflector and ducting- and you can eliminate the charcoal scrubber.

make it simple- screw the controllers and coordicating CO2 and fans- that's sooo 1986.

inject CO2, and just vent the heat from the light- not the whole room.

 

[pimpjuice]

If you have CO2- why would you want to vent the room?? Just seal the room and inject the CO2- al you need to remove is the heat.

Even if you use air cooled lights you end up getting heat build up from the lights, they aren't perfect. C02 burners also kick out some heat & humidity, you end up venting to cool the room down and drop the humidity.

Active intakes are nice because you can get the room cooled down quicker and get the Co2 ppms back up faster.

 

[darrinjefferson]

All of these thoughts go through my head, but the plants need fresh air as well. Its ok I decided to go without CO2. not worth the time, the hassle or the $$$$$. if I get awesome yields there is no reason to invest right now. in the future that might change.
Thanks for all the help everyone!
I am just going to use 2 good sized intakes with filters over them.

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[G33k Speak]

The plants don't need 'fresh air', the need CO2.

If you run air conditioning, I think it's crazy to vent.
if you don't have AC, I would still lean toward a closed room and CO2- YMMV.

 

[DIGITALHIPPY]

howdy everyone!
so I am about to start building my new grow room and I have still to answer the most key piece of the puzzle.

Should I use a passive intake or use a fan to blow air in?

I am using CO2 so I know everyone says the room needs to be sealed. The lights will be running on their own air line and then I will have a fan exhausting the room. The exhaust fan will be turned off obviously when the CO2 is on to avoid pulling it out. I just dont know if it matters if I use passive or forced air intake.
..

dude.. what can i say??? .. think about this for a minute. do you think the plants breath in ALL the CO2 you let out RIGHT AWAY??

so in your mind... you let out all this CO2 for plants to breath in, then you think its smart to then, go-ahead and suck it all out....????????
SO IN YOUR MIND that works well HOW???????

maybe some re-phraseing will help your mind think this through a bit better.

im just curiouse, because im about to tell you you need a sealed room.

i mean no insults, i just dont want you wasting alot of money on co2 just to suck it right the fuck out. my latest run cost me more then $180+ in CO2 alone.

 

[hoosierdaddy]

In terms of a grow, I would consider fresh air to be oxygen that had ~500-600ppm Co2.
And air supplied at that level needs to be maintained at the level. Simply pumping in Co2 can be lethal to plants when the ppm reaches ~1%.

 

[eyes]

right.the sealed room is a good idea but unless you have an a/c running i would recommend 1 vent per hour.ive yet to see a room run on co2 alone without a/c taking the humidity away or a vent per hour to do so.think about it...where is all that water vapor gonna go from the plant transpiration in a sealed room.you guessed it/in the air on the floors.watch that humidity rise and those plants choke off.best setups ive seen are ac driven and co2 enriched,and sealed.not just sealed alone without some venting.place a electronically controlled damper to open when the vent fan comes on .as a matter a fact have both your intake motorized and the exhaust motorized as well -that is if you are going to vent.that way you can make sure minimal smell /co2 is escaping.or,run an a/c with co2.yes,you will generate heat from the lights depending how many you cool even with air cooling.cheapest way to generate co2 is a burner/propane or natural.use the bottled stuff for small shows or during the summer.

 

[darrinjefferson]

well i guess i wasnt clear enough. I am not going to use co2. I can get awesome results without it so I am not going to waste my money right now.

digitalhippy- you are very far away from what I know and understand that its almost insulting.

thanks for everyones input.
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