co2 and venting

[cruseonme]

the guy at the hydro store told me i dont need to vent if i got co2 and the temp doesnt pass 85f......How do you calculate the fan cfm needed for the space?

 

[brushybill]

width x length x hieght, eg 4x2x8 = 64cf, so a 64cfm fan will move 64 cubic feet per minute, remember that venting also brings in fresh air, which plants like plenty of, so there are more reasons to vent than just heat issues. hope this helps

 

[tokemon]

I think the general rule of thumb is to exchange your air every 2 minutes minumum. I could be wrong. If I'm right you just figure your total grow area's volume by multiplying length times width times height then your fans cfm must be atleast half that number.

 

[The Hemp Goddess]

the guy at the hydro store told me i dont need to vent if i got co2 and the temp doesnt pass 85f......How do you calculate the fan cfm needed for the space?

While that is true, IMHO, you don't need to run CO2 if your grow space is well vented and you exchange the air often enough.

The ability to keep the temps under 85F depends on your individual set up--size of the room, the lights you are using, the cooling equipment you have for the room, fans...I know that I could not keep my room under 85 without exhaust fans, and my light is sealed and air cooled.

I think that before I invested in a CO2 set-up that it would be wise to see if you can keep your room temps under 85--coordinating ventilation and CO2 can get problematic.

I would be interested in seeing the results from identical grows with one using CO2 and the other not. I don't really know how great the benefits of CO2 are compared to a grow where you keep your temps under 80 and provide plenty of fresh air to your grow space.

 

[kasgrow]

If you have a sealed room co2 and ac you don't need to vent. My outside temps are in the 90's and 100's so there is no way to keep it cool enough without ac.

 

[cruseonme]

ya where i live its always passed 100's but another question is what about intake fan? does that stay on 24/7, i got a 700cfm fan for exhaust how often should it go on and off for a 15x8x7

 

[bizzy323]

bro if u got c02 don't bother with the venting, you vent for c02 or heat issues but if you got c02 and a/c you gonna get some big buds under 1000watts without any problems. aleast in a sealed room you wouldn't have to worry about spending money against odor control...my first grow was in a closet with no vent no a/c lol...i didnt get much bud but it layed a few people on there backs...if you go way back on the posts you will see some pictures....peace

 

[massproducer]

There are other reasons that you must vent besides CO2 and heat, namely humidity control...AAlso it is not quite that simple, if you are bringing air in from an A/C, then a similar amount of air is going to be looking to escape from your sealed area because of the pressure, so what that means is that with no venting system it will actually be a lot harder to control the odor, as it will seep out where ever it can instead of being directed by an exhaust fan.

IMHO, even with CO2, you need to have some sort of exhaust system to vent the stale air from the growroom. Most growers just set up there exhaust and Co2 on different timers.

While CO2 is wonderful as it lets your plants absorb more light, nutes and water, it is IMHO, very over rated by novice growers looking to improve on their first couple of grows. It is far more important to try and master the art of controlling the indoor environment, and then move on to mastering maximizing your availible space. Around this time you will start to hit your learning curve and start seeing very consistant results. This is the time I would say to introduce CO2 augmentation. To use cO2 effectively you must be the master of your environment, and your space must be maximized, or you are throwing money down the drain everytime you fill up your tank

 

[Roken]

Wassup,
I thought i might add to this thread, venting is necessary to all grows. You must get rid of the depleted co2 in the enviorment and humidity as stated above. It is common while running co2 to set it up on timers so while your pumping co2 in the room, your exhaust is off. Usually your co2 would run say for 5-10 min every hour at the begining of the hour depending on room size of course, after about an hour and a half this co2 is depleted and should be exhausted from the grow room while co2 is off, shortly after the exhaust stops venting your co2 system would refill the space again, it is very important to have your timers set exactly so you dont vent your $ out the room without using its valuble benefits. Hope this helps, peace and love!!!
Roken.

 

[bizzy323]

if you have two a/c units that is plenty of air movment and c02. everyone has different opinions i might be wrong but it worked for me in the past....just use exhaust fans for your lights and you be good..as long as you keep 70-80f in there.

 

[CasualGrower]

If you are venting with fresh air and your temps stay below about 85 deg.... adding CO2 to your grow will not help..(OK OK OK.. maybe not totally NOT help, but the effect will be minimal if noticeable at all)... Your plants will crave more CO2 as temps rise in the grow area. That is the main reason for added CO2.

 

[Roken]

The higher temps increase the plants metabolism with the added co2, they feed faster, grow faster and produce bigger buds when co2 is used correctly at the right temps. Each grower has his or hers own method but i used to keep my temps at 95f when running co2 and they loved it. Peace and Love!!!!
Roken.

 

[gcarlin_818]

sorry to uintrude on this thread guys but I have a ????.my set up is a
10x10x8 mylar'd.I'm in my 3rd week of veg and just bought a 15 lb co2 tank and regulator. Now I have done different grows but have never used co,I have alot of buddies who have used co2 and had outrageuos results when flowering.My ? is my room isnt light proofed as i really dont have to worry about unwanted guest's..I have a watercooled reflector so my temps are very controllable without a/c my room is at about 80 with a/c the room drops to about 72-75 should I throw the co2 in there and if I did would it be a problem with the leak from the door???thanks in advance Gil

 

[CasualGrower]

#1.... Light proof your room..... do thast before you worry about anyCO2.. or ventilation or anything else.... unwanted light in the bloom chamber is the BIGGEST stress a blooming plant could have..... Fix the light leak and then worry about the rest.

 

[gcarlin_818]

what should I use to light proof the room????

 

[CasualGrower]

Where are the leaks??? a crack.. use ducttape.... Door jams... be innovatative.... a big window, use black plastic.


On the 12 on/ 12 off cycle... it is best for light in the 12 on and TOTAL darkness in the 12 OFF cycle.... Now lil pinpoint lights or a superminimal glow is not all that bad... compare it to starlight or dull moonlight.... but since it is YOUR grow... and you are in control.... NO LIGHT IS BEST in dark time.

 

[gcarlin_818]

the leaks are comeing from the top sides and bottom just from the door being able to open.which leads me to my other question i still want to be able to get into the room so what would be best....?

 

[kasgrow]

I don't vent my room and it works just fine. My lights are cooled with outside air. The ac vents through a hose and recirculates the air so there is no addition of air. My ac unit controls humidity as well. There is no such thing as stale co2. The plants take in co2 and exhaust oxygen. You just have to keep adding co2 as the plants deplete it. With no ac there is no use growing inside here. If you vent you are wasting energy. I have a full garden of happy ladies that agree. The only time I would have to vent is if my ac broke down or my co2 stopped working, or my co2 levels got too high. Luckily none of these has happened yet. If I could vent the room I wouldn't need co2. In the winter time I don't need the ac so I don't use co2 and vent regularly.

 

[Roken]

Wassup Gcarlin,
What i've done before in that same situation was took a black plastic trash bag, you know those 25gal ones. I cut a strip along the the length of the bottom about 6 inches up, i then stapled this to the back of the bottom door, it can freely be opend and closed without tearing and when the door closes, it seals that bottom inch thats usualy exposed. I hope this can help brother, peace and love!!!!
Roken.

 

[gcarlin_818]

thanks a million roken...Really appreciate the help..im still in veg but I will still leak proof the room....