i have my design down my next issue is.....

my box is 54 inches long (L) x 20 inches deep (W) x 54 inches tall (H). im thinking of using a 600w hps/mh ballast or would a 400w be better? if it is any help i have astro foil all on the inside of my growing area.

thank you.

FADE

MORE LIGHT IS ALWAYS BETTER IF YOU CAN CONTROL HEAT.NEVER HERD OF astro foil...

i dunno if its a goot idea, sounds like a relativly small area ive just got a 600 and its hot as fuck, have to have it 30" awya from my girls ( flowering) temps are a bitch to get down

i have one 8 inch fan pulling air in from ground level and one 8 inch fan push air out with carbon filter, then up to the attic. in the box there will be one small bedside fan in the back and one opp. side. plus im tapping into AC which im thinking of just connecting the into the "in" fan. im just debating on 600w or 400w, hell even if i could get away with a 250w since i have the astro reflective wrapping, thats what im wanting to know!!! i know you get best results with a 600w, thats why i want to use that. this is just a test run so i can play a few times before a serious grow. any more thoughts from anyone?

https://www.rollitup.org/members/heath-robinson-34876-albums-heath-picture811857-19.jpg

astro foil

The foot print of a 600W is approx. 3x3. A 400W is about 2.5x2.5. Two 400W in that space would probably be a more efficient use of light. Not to mention more watts per sq. ft. To keep it cool, use one fan to cool the lights only. Use the other fan to filter and cool . A passive intake for cooling would be best. This set up is much more efficient than a fan on intake and exhaust. If you pipe in AC you probably wont need to exhaust. Of course you'll need to supplement CO2 this way as well as a dehummer after lights out.
Fred

With the height being only 54", I would suggest a 400w with a rectangular hood. That provides 47w per sq' and that is a lot of light. Most folks strive for 30-40w per sq', some may go 50, but that is in a room, not a grow box. Try to hide ballast outside of box, that will help some with heat too.

so it would be wise to make it taller by like 1.5ft correct to house a 600w? or just build a 3x3x6?

Okay, now I remember this thread. I selected the 400w over the 600w for several reasons. I only selected one 400w, not 2. the height of your grow space is ok, but with a 600w, the heat is going to be a lot hotter and you don't need that, you will be getting 47w per square foot. A 400w HID lamp covers approximately 16 square feet. If you already own a 600w or just have your mind set on one, yes, build a bigger cabinet to make it worth your while. a 600w can easily cover 20-25 square feet and maintain a high wattage to square foot ratio. Just be prepared to move some air through the hood and the grow space.

Fell free to PM if you have any other questions.

i will just go with the 400w! thank you sir. i will pm you with more questions if i have them which im sure i will. take care bro