Howzit TL?

I'm by no means a master, but I'll be happy to share what I have learned.


  • HID lamp: Source efficiency is typically 120 lumens/watt or higher. However, losses from trapped light, protective covers and lenses, inefficient ballasts and unfavorable operating temperature typically result in a measured system efficiency of 30 lumens/watt or less.
  • LEDs: Source efficiency can be 100 lumens/watt or higher, depending on the type and manufacturer of the LED used. There are no losses from trapped light due to the focused output of the LED, and secondary optics and protective covers generally reduce output by only 25% or less. LED power drivers are also more generally efficient than HID ballasts, and reduce system efficiency by 10-15%. However, even when efficiency reductions due to high operating temperatures are included, LED system efficiency often remains above 50 lumens/watt or higher.



That is base on 2007 figures and on the surface says that HPS produces 2X the lumens per Watt.
That is because it measures lumens.
We are more interested in the PAR value, yah?

Attachment 298270

The bandwidth of sodium vapor is less than ideal for growing weed.
Much of it is not absorbed.
Makes the leave look bright yellow as it bounces off.
What does get used has to be up-converted by the plant, and that requires energy.
There goes your efficiency.

White leds are not that much cheaper to run than T5s or CFLs, until you factor in replacement costs.
For short term use, (2 or 3 grows), with full spectrum light, I would use T5s or T8s.

Where LEDs really shine, is narrow bandwidth lighting.
I target the absorption peaks for Cannabis and waste no watts on the rest of the colors.
That includes IR and UV.
10 Watts of well targeted light is worth about 18 Watts of white light.

So, it is my opinion that 1000W. of full spectrum light is wasting a substantial amount of power on less productive illumination.
~600W. of targeted leds will pull the same weight.

There is added advantage to di-chroic lighting in control of the morphology.
Increase the blue and the internodes stay short.
Increase the red and we make them stretch.

Now, I'd like to address the proximity.
But my wee beasties are wanting attention.

I'll save it for another post.

Suffice to say that keeping LED lighting too close to the canopy is a bad idea.

And it's not just light saturation causing growth cessation.

Think, Inverse square law vs. plant height, alright?

Attachment 298269
 More later, or upon demand.

Aloha Y'all
Weeze
Weezard Reviewed by Weezard on . Help with lighting please All plants are in same grow room, two of them ready for 12/12, 4 still need 18/6, is it ok to put the light to 12/12? Rating: 5