Four in that space would be a complete waste of electricity, but I would absolutely suggest a cooltube. It will let you get them down even closer and you're already golden on light in that tiny cab.
Post number 152 in this thread shows a cooltube made of a candle chimney that costs $10 at the big craft stores:
https://www.rollitup.org/indoor-growing/106339-150w-hps-club-inspirational-resource-4.html
Plus four 150's is 740watts of power consumption when you add ballast losses. Save your money for later when you have more room and need a larger light or for some new beans.
"You think I might need more CFL's or 2 HPS to balance the lighting evenly?
Its not worth running 2 HPS 150w lights, that would create a fair amount of heat, also, 2x 150hps will not create an even color, as both HPS emit the same color spectrum light 2000-2700k that is suited for flowering, altho a HPS bulb will veg a plant reasonably well, you would get larger plants during vegging if you used a MH light,as they are more suited to vegging due to their very blue color rating 6500k......."
Very good info on that post there....as many times as i've been on that thread, I can't friggin believe i missed it. In a perfect world I would have a 400w digital ballast but as it stands, i'm a broke mammer jammer till long after the holidays but i've only got 4-6 weeks to go b4 the chop so i'm in a tizz to get more lumens to my babies so I can fatten them up to the max.....even if i'm using less than efficient equipment to make it happen
It seems like the person that posted that was more or less just saying the heat buildup from using multiple 150's would not be suited well for the micro-cabs they're being used in...my situation however is different b/c I do not have a ventilation issue. As far as the extra power consumption goes, not a big deal....if I had 10 of these things going i'd say it makes sense to address that concern but w/3 or 4 I believe it to be an even trade-off. If I really wanted to go overboard there, I could put 150w horti bulbs in there w/added blue spectrum which would address the other issue on his post about the appropriate light spectrum.
In a nutshell, i've gathered that this can be done with the following pro's & con's:
PRO: More lumens / more even distribution of light / larger flowers
CON: More heat to dissipate / wasted energy due to inneficient equipment / no blue spectrum (unless you buy replacement bulbs)
For me, the pro's outweigh the cons since heat is not an issue for me & I don't believe the lack of blue spectrum outweighs the availability of an additional 15,000 lumens for the plant to soak up.
