Passive intakes

Hi! I have 47x53x120cm grow box.. Using 250W hps and 1x 12 cm PC fan as exhaust...and i dont know how many passive intakes should i make and how big they should be? In my opinion its would be 2x 12 cm holes at the botom and the opposite side of exhaust.. Is it good ? Thanks for help

Sure, that would be plenty...just make sure they don't leak light.
JD

okey and when i will use intake pc fan too? like this https://www.rollitup.org/members/farmingtoronto-60163-albums-new-intake-fans-picture792866-2-120mm-pc-fans-intakes.jpg ? its ok?

Blint,
You asked about passive...which means no fan. If you want to use an intake fan...then you will only need one intake opening.
JD

JohnDee said:

Blint,
You asked about passive...which means no fan. If you want to use an intake fan...then you will only need one intake opening.
JD

Click to expand...

Okey sorry and what you think ? Its better passive or fan?

I've only done large grow rooms and I always used passive intake and a large exhaust fan. You'll have to decide depending on your fan strength.
JD