any suggestion for proper ventilation

hi
I would like to buy a ventilation system. Just not sure which one would be right for me. My tent is 2.4x1.2x2m. Currently I am running 2x400w MH, at the flowering thinking to run 3x400HPS. at present temperatures in the tent is from 27-28C with two lights, obviuosly when will have 3x400w HPS temperatures will be higher. I do have a fan that is capable of 187m3/h, but thinking to use it as intake as now I have only 2 PC fans for intake, which is not enough. So, would u be able to offer for me something that would be most suitable.
Regards

simple 8 inch can fan, u might get away with a 6 inch but i doubt that as 1200w hid produces alot of heat. A 8 inch would also keep negative pressure when using it as exhausting and your current fan as intake, meaning no smell leaks. peace

cheers m8. right so 8 inch fan, how many m3 will absorb per hour? and here what size carbon should i get for this kind the fan?

thanks for ur replay, bigbudahluva

i have two adjoing rooms. i am using a 6", 440 cfm (on half speed). i had to put a 6" port from one room to next, and one in other which leads to garage. no smell leaks, as its a one way action, from garage, to filter! i think i should add a port on each tho. otherwise, it is hard on the ol fan, if not getting enught air flow.

so, here, guys, this one as extractor http://www.ebay.co.uk/itm/8-Inch-Fan-Filter-and-Ducting-Kit-Rhino-Filter-Ducting-with-RVK200-E2-A1-Fan-/310409987811?pt=UK_HomeGarden_Garden_PlantsSeedsBulbs_JN&hash=item4845e086e3 and this one as intake http://www.ebay.co.uk/itm/Vents-TT-100-Hydroponic-Grow-Room-Tent-In-Line-Vent-Extractor-Fan-4-187-m3-hour-/130620453534?pt=UK_HomeGarden_Garden_PlantsSeedsBulbs_JN&hash=item1e6995f29e will it do job well or intake needs to be more powerful?

This might help, too....the general formula for "How big of a fan do I need?":
http://cheaphydroponics.com/Merchant2/cfmcalc.htm

Also add 5% for each aircooled light, 5% for CO2, and 20% for a carbon filter. Really humid climates may require more, but this is a good rule of thumb.

get the fan and filter as a package usually cheaper and correct sizes. goodluck m8

oh and that 8 inch ruck u found on ebay is perfect, u could get away with no intake as ud have neg pressure, i use a 12 quid fan for intake off ebay try have a look if ur set on intake. peace