u havent done ur reading, that box is going to need alot before its done, first off its to small for those HID lamps, with just a 150w my box which isnt that much smaller then urs gets up to 100 during the day if its warm enough outside, about 20 celcius would do it, so if thats staying inside ur gonna have to look into a really fat exhaust fan, if ur still having trouble maintaining a cooler temp, look into moving it into a basement where it will be colder, also try running it at night as temps are usually cooler at night. definatly put doors on the thing, with 2 different light cycle u cant have the light seeping inside when one is on and one is off. I just use tarpoline folded in half with velcro as my doors, it works really well because u know its lightproof and its very inexpensive. the box thing im guessing is a kind of makeshift cooltube, its use pyrex or something like that instead, hook it up to some piping and u can have all that heat from the bulb going right outside and heating up the surrounding air alot less. In all honestly ur probobly going to want to use t5's or Cfls for that bottom cab, its just to small for an hid lamp, ur going to need about 8 inches for a 1 gallon pot, plus the plant should be around 1-2 feet when ur flowering so u need that much room in the bottom... when i first made my cab i ended up moving my shelf 2 times before i had it at a good height.
