My cabinet is pretty close to those dimensions (20" deep, 6' high, 4' wide), and I have a 400 watt HPS in it. The (digital) ballast is in there too. I have no problems with heat - I run 3-6 degrees higher than ambient, and it's not been difficult to keep it in the 75-77 degree range. I'd say the light is about right, but I also run eight 26 watt flouros in there for accent/sidelighting, for a total of 604 watts, and 65,000 lumens or so. I do use a cooltube and a 440 CFM 6" centrifugal inline fan (dialed way down speed-wise because that's an awful lot of fan power for my cabinet). You can get your plants quite close if you go the cooltube route - I've had no problems getting within 4 or 6 inches. But to provide better spread over the width of the cabinet I usually keep it a foot or 18" away.

400 watts isn't the highest you can go either. There was an interesting growlog on overgrow (R.I.P.) by a guy who had a really nice looking armoire about the same size as my cabinet. He put a 1000 watt light in there and had no problems. He did it knowing that that much light was way overkill, because he wanted to see if it was doable (it was), and because he already had the light laying around. Personally, I think a 400 is just about the right size, and any more than 600 would just be a waste of electricity.
jamstigator Reviewed by jamstigator on . HPS 400 sufficient ? ... heat ? I have grown exclusively with Flourescents for many years, 320 watts of 4-footers, because I just never wanted to deal with the heat put out by the sodium lamps ... but, I am thinking of experimenting with a 400-watt sodium at the next flower time ... my cabinet is 2ft x 4ft x 6.5ft ... would a 400w be sufficient , or just barely ? ... also, how much heat will the 400 produce ??, finally, how high above the plants would the 400-watt HPS need to hang ?? ... thanks in advance for answers :smokin: Rating: 5