I understand what you mean as far as being bound by heating conditions, just a thought though so you could manage the HPS...

You could get a 6 inch hole saw and then get a 6 inch inline fan, problem solved, yes it will cost you a little bit of money, but the payoff would be far greater than that of using CFL's. Just throwing idea's around that's all.

If you have the means, by God, don't be stingy lol.

Pro's of HPS:

Higher overall yield vs. CFL or any other indoor lighting.
Higher quality Bud.
More Lumen output (thus imitating sunlight better than CFL)
Longer lasting than CFL, hands down.

Say you have 6 x 42w CFL = 16,200 Lumens
Compare that to say 400W HPS = 50,000 Lumens
No comparison really.

HPS systems have better Lumen per Watt which means less heat per watt. They also have a much higher PAR which is a measure of how much light is actually used by the chlorophyll. PAR stands for Photosynthetic Active Radiation. CFL's are a waste of money, electricity and time.
HPS = More PAR per watt/less heat per watt.


Cons of HPS:

Heating extraction, thus need sufficient air intake/outgoing. (Why I mentioned the DIY cooltube)
Initial cost.
Energy bill goes up about $40 a month using a 400W system 24/7. Really not that bad.


I am not an advocate for either, I just know what lighting is far superior for plants, when growing its better to get the "best bang for your buck" so to speak. In this case, invest a little more money, and get a better payback. But I can tell your mind is already made up, just some additional food for thought. I support you no matter what you choose, just choose wisely


p.s. if you do choose CFL, would you be willing to sell your HPS system, I'll take it off your hands, how many Watts is it?