How much CFM needed to cool a 150 watt hps in a rubbermaid grow

The plan is to put a single 150 watt hps light ( not a cool tube ) in two 32 gal rubbermaid bins stack atop each other. I want to hang the light from the top obviously and have a 6 in axel fan ( rated at 250 +/- CFM ) as an exaust fan with one or two passive intake holes on the lower portion of the side. Its about 3.5 cubic feet in the bins. So the fan would clear out the air about 71 times per min ( 4260 times per hour ). I will be lst'ing the plant i put in there so it wont be so close to the light. Any advise would be awesome. One question in particular is should i place the fan over the light on top of the set up? Or on the side twords the top?
Thanks in advance.. Happy smoken:jointsmile:

3.5 cubic feet is very small.... You will not only have heat issues but space issues as well even if LST'ing, IMO....

But when it comes to exhaust, it's better to have more than enough than not enough....

CGI::::::

Im not quite worried about space. Ive seen many awesome rubbermaid grows and thats the space im looking for. And in terms of more exhaust power the better, for the amount of space that im using 250 cfm wont be enough?
Thanks for the response =))

I messed up the space would be 8.5 cubic feet and heres this:
Originally Posted by stealthy44
i would go with the hps if i were you. look at the 150 watt hps thread on here, i believe the OP used a 150 hps in ONE 25 gallon rubbermaid- with only computer fans as an outtake. in my opinion, it should work as long as you are smart about it. meaning dont let anything extremely hot (which the light and socket will be) touch rubber, or your plant for that matter. also make sure you have a fan or two blowing directly on the hps, for obvious reasons. and good ventilation in general. if you are planning two stacked on one another id say a 6 inch duct booster will be enough, provided you still have an intake and circulation on the inside.

are you really thinking of getting 500 watts of cfl's instead of ONE 150 hps? im pretty damn sure those cfls will put out more heat.

Ive built it, Check out the journal page in the next couple of days while i get my pics in order. Thanks to CanGroIt for the advise. so far with out my bins being light-proofed, the fan does a great job with passive intake, not even a fan inside for circulation and its still really cool inside the box. Im going to put foil tape around most of the inner part of the bins. and figure something out for the outside if that doesn't do the trick.
Cya later