Negative pressure query

[FatBagz]

Hi everyone,

I finally have all my equipment and will be setting it all up this coming weekend. I've been doing last minute research more specifically on negative pressure. This will be my first attempt at growing (anything for that matter). My tent is a Jardin DS120 which will run a 6" Rhino Fan (twin speed) & Filter (L1 version).

My question is, how do I maintain negative pressure inside my tent? I read somewhere that feeding some 8" ducting at the bottom of my tent coupled with the 6" fan exhausting the air will create what I need. Can anyone shed some more light on this for me? Can someone explain to a noob like me haha?

Thanks for your help guys. I can't wait to start my first grow journal for you all to see

FBz

 

[millertm]

Are you running bare bulb? I have a 560 CFM fan feeding my 4x4 tent 6" fan. Another 6" with carbon filter ducted out window. Slight positive pressure when running. Tent is not blowing up or sucking down. Room at 66° tent peaks at 78 cycles off at 73, fan on at 75. Running 1050 watts bare bulb.

Cheers

Sent from my SPH-L720T using 420

 

[FatBagz]

Hi Millertm,

Excuse my lack of knowledge but by bare bulb do you mean non hood cooled? My light is 600w with just the standard euro reflector. I will need to maintain negative pressure as to keep the smells from leaking out. I will be going for passive intake rather than another fan bringing cool air in.

My fan on speed setting one moves 390 m3/h & speed setting two is 760 m3/h.

How would I create the negative pressure needed? Will the tents own vents be enough to create the vacuum or will I need to run some larger ducting (8 inch so I've heard) through what would be the intake port?

Sorry If I'm making no sense haha

Thanks

FBz

 

[millertm]

With no air into tent, 600 watts is to hot. Most tents will have too much negative pressure and run hot. You will need two fans for your setup. I'll get some more pix of what I'm talking about. Smell is scrubbed with carbon filter. Look at my journal around page 10 or so, I have my setup there. You need to move as much air as possible to run bare bulb.

Cheers

Sent from my SPH-L720T using 420

 

[FatBagz]

Hi Miller, from what I've read so far. I don't NEED another fan bringing in cool air even with my 600w light. As long as I have a good enough extraction fan (I think mine is more than suitable) passive intake should work absolutely fine. This is the post I'm talking about, can anyone confirm this is correct?

"Quote"I have the same tent as you. You dont need an intake fan. Passive intake is all you need to control airflow and maintain negative pressure. If your exhaust is 6", just get a piece of 8" ducting and put it on one of your lower duct ports, then put at least one 90 degree turn in it to prevent light from getting in. Point it towards the ground if possible.

With my tent and an 8" duct for the passive intake, airflow is perfect with enough negative pressure to suck in the tent slightly but not so much that it causes the frame to bend. "Unquote"

FBz

 

[millertm]

Well in theory your right. My 440 CFM turns my 4x4 tent over 3 to 4 times a min. Without added air tent sucked up tight and ran hot with 400 watt MH bulb. Putting 8" duct in a vent will help but might not do the trick. It depends on room temperature. Try it and see if you can stay under 80F.

Cheers

Sent from my SPH-L720T using 420

 

[FatBagz]

Thanks for your input Miller. I will give the 8" ducting a go and see if it works. My tent is in a well insulated shed. I'm not sure of actual temps but the air in the shed is very cool so I'm hoping passive intake will work just fine.