Ventilation quetion

Hi. I am in the process of setting up my first closet and have a couple of ventilation questions I need help with. I have built a 6'x4'x4' closet with a 200mm hole in the roof for my exhaust fan and have a 250mm hole in the bottom right side for the intake. My exhaust fan is a simple 268cpm fan /w 3 metre of ducting and I have yet to purchase a fan for intake. I have 600w HPS light and will have an oscillating fan inside as well to help with airflow.

So my questions are:
Is it ok if my intake hole (250mm) is larger than exhaust hole (200mm)?
Is it sweet to buy 2 x 268cpm fans and just spin 1 for intake and use other for exhaust, or should one be weaker than the other?
Do you think my fans will be sufficent given the 600hps and size of room?

thanks in advance

sound ok to me. heat rises so if you have a fan and ex. at the top you should be fine.
craige

your computer fans will not properly exhuast the heat out of your closet, especially if its sealed. Your going to need to do two things: first, find a way to direct the heat from your light out of the box or room...most hoods have an exhaust hole and way to slide in a glass shield. Get dryer vent and hook it to the end of the exhaust hole on your hood and suck it out.

your other option, is to buy a bathroom exhaust fan (cheapest way to go) from Home depot. Cut out a good sizes square at the top of your box and place the exhaust fan on top. The exhaust fan will suck out all the heat from your box out the top. This is the method i use and it works well. afterwards use those computer fans to bring outside air at the bottom and you should be good.

The exhaust fan I have ordered is [FONT=Bitstream Vera Sans, sans-serif]a 200mm Lenco, ball bearing fan for continous running 268 m[FONT=Arial, sans-serif]³[/FONT]/hr takes 250mm ducting. I don't think it is a computer fan, as those only do minimum air movement (10-30cfm?) and I don't want that. The shade I have is a [/FONT][FONT=Bitstream Vera Sans, sans-serif]900mm x 800mm, silver dimpled shade.

I went here ACF Greenhouse Exhaust Fans & CFM Calculator and calculated cfm required to move air through 6'x4'x'4 and it is 115cfm - so I'd assume my 268cfm fan is enough.

My only question now I think is do I need an intake fan or is passive intake fine?
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You will be able to determine this by doing a test. Generally passive intake should be twice as large as the exhaust. VV

Cool. Thanks for the reply.

Can I have a, say 250mm intake fan that is more powerful than a 200mm exhaust fan? Is this advisable or should the stronger fan be exhaust? Thanks, this ventilation thing has me confused