Help with ducting for a cabinet grow

hey
So here is a draft of the cabinet I am going to grow.
I forgot the dimensions on the image

Length 1.6 ft
Width 2.6 ft
Height 6.2 ft

http://imgur.com/XFIEG



Any suggestion on my ducting?

I was planning on growing Lowryders n other Auto's in soil.

what you've got pictured will work just fine. Simple is always better and thats as basic and trustworthy of a setup as any.

You sure you got the length and width right? seems tiny...1.6 ft???

well its a cabinet.

length 19.75"
width 31.25"
height 73.88"

for autos, will there be a difference in a 250w hps or 400w hps yield?

Higher wattage = more bud.

So I just have to vent the cabinet/light well enough to keep temps down. so after the filter and ducting the 8" fan should to just fine.

shouldn't there be two balance dampers for finer control and the carbon attached to the inlet of your cab draw (the duct, not the passive)?

these are things i need to know...

Hey Derruti you got the right idea. But if I could offer you some help:

• Your cabinet has 25 cubic foot of air - so a 25CFM rated exhaust fan, without ducting of filter, would replace the air in your cabinet in 1 minute. An 8 inch fan is typically rated 500 - 750CFM. Even with massive restriction and miles of ducting, your would still have a hurricane in your zone.
• Use approx 200 CFM fan for exhaust. A standard 4" fan is rated at approx 200CFM. Unducted, this will replace the air in your cabinet 8 times per minute. Once you add your filter and exhaust run, your CFM's will be reduced, but you will still have ample headroom.
• Rather than two 4" dampers in a cabinet this size, run just one 4" intake SMALL inline DUCT fan (less than 100 CFM), with a HEPA grade filter (DustShrooms are nice alternative to the standard weave style HEPA filter offered by most).
• With both an exhaust and intake fan, you can maintain a balanced pressure within your zone, rather than relying on overkill exhaust fans and negative pressure to open dampers for intake.
• Kick these fans on and off simultaneously with a temp/humidity controller.

Oh yeah - and keep it simple! haha I like that one too KISS