Ventilation

I'm going to start a small grow with just one plant. It'll be in a 2.5 X 2.5 X 6ft area. I'm getting ready to buy an inline fan, but I wanted to know if I should go for a 4" or 6" fan. The ones I'm looking at there's a $10 difference, and it's 171CFM vs 435CFM, so originally I thought the 6" was a no brainer. However, I'm new to carbon filters and was told they work better if the CFM rating, on the filter is much more than on the fan. Did I misunderstand this person? Which should I go with?

Get the 6 and a speed controller. Better to go with more then not enough, especially if you ever want to expand.

i thought about expanding, but decided if I did that I'd get all new equipment anyways. This is just for a small grow. Also would 400w be sufficient if I was going to Scrog, or would I benefit from the 600w?

Also, any input on the CFM rating of the carbon filter?

The 400w is fine, it's a small space. If your going to expand, that space is perfect for cloning, vegging or isolating a female to pollinate.

What mightyBUM1 said about fan- you'll want a speed controller either way.

As a rule of thump a 400W will cover 3x3 ft so its plenty, just remember, they get REALLY !!! hot

About the CFM, you need to be able to exchanges the air in your grow room every 1-5 minute, with a big HID light in there, every 1 minute would be best as its not only for fresh air exchanges for your plants but also to keep your temperatures on track and I must strongly advice you to get a cool tube or hood for such a small room with big HID light

the CFM on your filter indicate how much it can handle, need to be able to handle your ventilation or more, so the CFM on your filter have to match it or bigger

if you go with the 6" (I would) you need a filter that can handle it, also remember that when you add a filter your fan will "loose" about 20-30% of its power/effect so take that in to account as well


when I began to grow I had a 600W in a 3x6 ft room (sealing hight) and after a few hrs of running it made my ambi temperatures in there go up from 22-24C to about 34C !!!!

after I got a 6" ventilation I could keep it under the 30C with 22-24C ambi temps out side, running it at night made me able to keep ok temperatures to grow, but at summer time it was still above 30C

first when I did add a cool hood to the 600W/6" I got it down to them 26-28C (now I use LEDs and can keep the temps 1C over my ambi temps out side)


so if it was me with your space, a 400W MH/HPS a 6" vent with a filter to match and a cool tube would be what I would go for, with one or two plants in a scrog