replacing air question

730dipdip187

730dipdip187

Active Member
how many times would a grow tent air need to be replaced? i heard from some its like 3-5 times a minute then from some i hear its once every 3 minutes or some shit. then i heard its like 3 times a hour. im confused

and with that being answered how many cfms should my fan have with a 4'9x4'9x6'7 room
 
Well, 5x5x7 is 175 cubic feet, so depending on how often you want the air to replenish, that will tell you how many cfm you want your exhaust to move.

I'm new too, and I will be moving air according to the temp and humidity in the grow room.
 
usually 5 times is good. multiple your dimensions together then multiply that by the amount of exchanges you want to do in an hour (5) and divide it by 60 (amount of time in an hour) this will give you your recommended CFM
 
well how often do u want to replace the air? is it 5 times in a hour? or 3-5 a minute? or once every 3 minutes?
if times 5 times a hour that would mean i would need a 14 cfm fan? that doesnt sound right
if i do it 3-5 times a minute i would need 525-875 cfm fan right?
and if i did it once every 3 minutes that would leave me using like a 60 cfm fan?
i dont get it
 
what are your measurements in? It should be in feet as CFM = cubic feet per minute 5 x 5 x 6.7 = 167.5 x 5 = 837.5 / 60 = ~14 cfm

The book I bought suggests at least 5 exchanges. Just buy about 250 CFM, theres really no price difference in fans
 
my tent is 4'9x4'9x6'7
rounded off i juss did 5x5x7 which is 175x5=875 which also comes out to 14
so ur saying i need a fan that 14 cfm?
and are u saying 5 times a hour or minute?
 
well I don't have the book any more buy I know it was 5 times and I'm pretty sure it was an hour. I looked the information up to make sure and they said the same equation as I said and also said 5 times an hour but this was for a bathroom. The website's answer was also really low

I plan on building a room in similar size though and plan on using my 250 CFM fan that I bought for my old closet grow.
 
more exchange the better, just have a place to put the hot air like an open window or something
 
SticherVA said:
You will need at least that. Remember if you are going to use cool tube or a charcoal filter you will not get close to the rating. Much better to go larger with a fan speed controller, Than get stuck in an overheating situation.
Click to expand...
would a 650 be good enough goin thru a carbon filter and light? i heard some fan speed controllers burn ur fan out
 
you should replace air minimum 1 time every five minutes. so for your room you would need at least 32 cfm. personally i like to exchange air 1 time every 2 min or so.
 
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