Too bad my digital camera is not 3D.
That one 20W tube you see is actually 18W (europe 230v) but it has 5 brethren, totalling 108W. (dimensions : 2ft x 2ft) about 1200 lumens each for 7200 lumens total.
I chose my fluros carefully, most people i read about on the internet using fluros prefer color 830 (3000K) or 840 (4000K) because they output 1500 lumens for 18W :
830
840
but I chose 33 (4200k) because it has much wider spread spectrum, not those nasty skinny peaks, although it only does 1200 lumen for 18W:
color 33
I remember reading that the optimum wavelength of the light for photosynthesis are around 444 and 666 nm.
I chose long 2 foot tubes instead of spirals on purpose, because of the increased surface area emitting light. This should be better to spread the available photons on the plants more equally = better efficiency.
In the first two months of growing, temps here in my grow box were a bit on the low side when the lights were turned off.
All the way down to 10 Celcius, thats like 50 Fahrenheit.
I noticed that slowed them down a quite bit. Good thing for me the summer got going around here, but my next winter grow I will add more power and more light for better temps.