Okay heres my newby set up bare with me trying to upgrade lol i have a 150whps an 2ft 4tube t5 in my customized refrigerator hydro set up the dimensions are 2 by 2 1/2 by 5 do you think a 400w hps would be ok in there heat wise because im already haveing slight problems with my 150w but i think its because the 150 has a built in ballest not to bad tho around 85 when lights on. Or should i just go ahead an save some more money to build a 4 by 4 grow room but if i do that i also have to buy inline fan an carbon filters because il have to switch location of room cant have it smellin in the other room lol. Which would be best / cheaper
The 400 will have an external ballast so that will help alot. I had a 150 in a small spot and had to take the ballast out which dropped the temps greatly.
consider going LED if you can. you won't have the heat issues. and since you have to change bulbs every year (my hortilux 430W are about $90) and uee so much less power, the LED would pay for itself pretty quick.