How much ventilation?

[FlyBoy]

I have 40x40x60cm box and i will put 150w mh(for veg) and 150w hps for flowering....How much cfm i must pump in and out to cool the box and create some negative pressure(to smells will not leak out)?

thanks!

 

[shabx1422]

do u have any air circulation in the box (FANS-BLOWERS) plants loves fresh air so it would b good to have a place that old air is being taken out (OLD STALE AIR) and a place for clean air to come in. then the fans circulate this ait around for your ladies to grow. as to the smell get a carbon filter they work extremely well they have something in a liquid form that is suppose to work well not sure i hope that info was helpful .

 

[hazyatbest]

figure out the cubic feet of your container. they say you need to exchange the air every 5 minutes or so. if you have a 100 cubic foot container, you need a fan that will pull approx. 20 CFM. you have to have an intake hole that is bigger than the exhaust, or the fan gets back up, and i think that might create the negative pressure you were talking about. i might be way off on this, but i'm pretty sure the size of the holes goes hand in hand with the pressure problems.

 

[Aberration]

Small holes on the intake, large exhaust thru carbon filter. As long as the box is otherwise sealed and the fan never shuts off, no smell.

Start with small intake hole(s) and test. You need enough air movement and no more. If not enough air is circulating, increase your intake a little more until it is. Never let your intake get more than 1/2 the exhaust in area.