grow box heat control issue

[sitjaspliff]

hi i have my grow box installed with 2 pc fans to exhaust air out and got one pc fan for air intake... an one oscilating fan inside.. i have been using cfl grow lights with ease temps stay up around 75 degrees but i tried with a metal halide and it soared up to 90 and above.. so got any advice on what i should get... im not to worried using cfl's as its in veg state but i when i start flowering i want to be able to use my hps without problems.

sitjaspliff Reviewed by sitjaspliff on 05-05-2009. grow box heat control issue hi i have my grow box installed with 2 pc fans to exhaust air out and got one pc fan for air intake... an one oscilating fan inside.. i have been using cfl grow lights with ease temps stay up around 75 degrees but i tried with a metal halide and it soared up to 90 and above.. so got any advice on what i should get... im not to worried using cfl's as its in veg state but i when i start flowering i want to be able to use my hps without problems. Rating: 5

[disrupt86]

pc fans are your problem.how big is the box and what size is your mh,anything over a 150 in a small box is going to need at least a 135 cfm fan.

[sitjaspliff]

thanks for reply my box is real small- its like 2ft X 2ft X 3.5ft something like that anyway- its 400w mh light ballast is outside grow box.- how many fans with the 135cfm will i need are they all extraction then??