BigBudBalls
Well-Known Member
But it makes through the glass of the bulb? Help me understand that.UVB can't penetrate glass, therefore it's lost....
A cool tube is curved glass, so the optic index is skewed. You have the natural index (usually about 1.52) then adding in the curve.I've seen both independant opinions as well as real tests on footprint and focused light from different reflectors, I've never seen a Cool Tube come out on top or close to it. I understand that there are set ups that people build that they may need one because of size, ventilation, ease of use, lack of engineering ability, or something, but, I've never seen any commericial growers using them in a large set up. I'm just guessing, I don't grow at that level, but, Im pretty sure it's because a large hood has always been shown to be better. Cool Tubes are cheaper then large reflectors, so why don't the pro's use them? I know the reasons I've read but, I'm certainly open to hearing how they maybe wrong.
For those of you that don't remember, I'm the one that started this thread. I've been through veg and flower with a 400 watt CMH bulb. I don't flower under the CMH anymore, for no other reason than I have a flowering room running 1000 watt bulbs. I do still use it for veging in the cabinet. MH doesn't compare for vegging, I saw it for myself. As for flowering, I can't give a true opinion, I have not flowered under 400 watts HPS at any point to be able to compare the differance.
With a flat glass (air cooled hood) all you have is the 1.52 index and any coating that might (probably not) are on the glass.