Okay so i recently got a primaklima 125(5 inch) one speed fan (360m3/h/211CFM) but i found out its way too loud when running at full speed so i got a RPM adjustor and insulated ducting and set it to 70% speed( should be around 250m3/h-150CFM now which is good noise-wise). Okay so now im running my fan below carbon filter optimum airflow which is 360m3/h. Im afraid i wont have enough negative air pressure inside my tent and the smells will escape. Now i wanna know if i should get a smaller carbon filter which is rated 240m3/h-140CFM ( prefferable because my current filter is 400mm long and the new one would be 250mm long and my tent is only 90x90 so i wont have space issues) or should i get a bigger fan and run it at lower speed, or would closing one of the passive intake holes do the trick. Have a great day
Question about negative air pressure inside grow box
- Thread starter lychas420
- Start date
Renfro
Well-Known Member
The filter will perform well at the lower speed, actually better single pass scrubbing performance with lower air velocity through the filter. You can outrun the filter by pulling air too fast but slower just means it can scrub the air better. It's about exposure time, the faster the air moves through the filter the less time the carbon has to trap the odor. So the filter is good to go IMO.
Closing a passive intake would definitely increase the negative pressure, if thats all you are worried about (odor) and heat doesn't become an issue then that might do the trick for ya.
I always like to oversize my fan and put it on a variac to slow it down. Some of the other speed controllers will make the fan "groan" due to the sine wave being clipped so I really prefer a variac, a real variac is a variable transformer with a knob on it so you can go from 0 volts to full voltage and anywhere in between. Some "pretend" variacs are just a multi tap transformer with a selector switch for the taps, so you might have 25%, 50%, 75% and 100%, these will not beat up the sine wave either since it's a transformer so if you are fine with those speed selections you can use one of these.
Another nice thing about an oversized fan, if heat becomes an issue you can turn it up a little.
I run a vortex VTX 10 inch fan on a 2x4 tent lol, I turn it way down and it is still trying to implode the tent but you really can't hear it running at all.
PadawanWarrior
Well-Known Member
Holy shit. A 10" fan lol. I have a 4" intake and 4" exhaust fan that I leave on high in my 2x4. I actually have positive pressure in there. It gives me a little more space in the tiny tent. It's not quiet at all in my room, lol.
Renfro
Well-Known Member
Remember when I posted about those 10 inchers being on sale cheaper than the 4 incher? Thats when I picked that up, I was looking at just a 6 or 8 incher slowed down but the 10 incher was cheaper lol
Renfro
Well-Known Member
Please critique my grow space and equipment. Journal coming after set up!
Hey RUI. About to set up an RDWC grow room and just thought I’d share my room and set up. I see there are various pages for lighting and hydroponics but I’m going to try to clump all my set up stuff here, and begin my journal after I’m finished completing the room, and I’ve germinated my seeds...
www.rollitup.org
That was one place I posted about that sale. $114 but of course that deal is long gone now lol.
PadawanWarrior
Well-Known Member
Nice. The 4" fans are the cheap Active Air ones. I bought a 6" VTX when I saw that sale. I should've grabbed a 10" too.
I've bought another 6" VTX since, so I have 2 now. The rest are the cheaper ones. The cheap green ones work pretty good too though.