came home for lunch
ever ride a bike and get a sunburn because the wind made it so you didn't feel the sun?
ever notice that if is 80 degrees outside it feels hotter if there is no shade?
ever compared the temp between shade and direct sunlight?
this natural relationship is the most misunderstood tool in our arsenal. Plants are little machines when everything is dialed in properly (everything includes ALL elements) Plants want heat, they want the canopy to be higher (temp) than ambient, a 12 to 15 degree difference is ideal (and very hard to get in a sealed tent or room) In my room I keep the ambient between 74 and 78 degrees, I keep my canopy between 89 and 92 degrees, You can not do this with a cool tube !!! Not to mention that the photons from your light are passing thru glass before they get the plant, some of which is degraded, some never gets thru (a light meter would show you this)
If you go to
http://growhappyplants.com/ and look at all the pics (on several pages) you can see my canopy temp/humidity are at 91 degrees with 42% humidity (gotta look close) you also see that I have T5's over 2 feet away from the top of the canopy. This area is in a 500 sq ft room that is completely open !!! which is why the ambient is only 78 degrees, the only place the room gets hot is under the lights at the canopy. Temp measured down by the pots is 78 degrees (same as ambient) which translates in to root zone temps (which are just as important)
Most simply do not understand these relationships, Hell I took a 50 watt LED light and made it grow just as much as 2 400 watt CMH's and the LED was 5 feet above the canopy (yes I have pics) Folks can bash the stuff I say all they want to but I'll continue to stand on, the truth is always the truth