Light distance?

[GuitboxTom]

I’m now wondering about relative light distances. I know that all the “hot” lights ie HPS etc... need plenty of space from the top of the canopy, but with LED quantum panels the recommended distances are closer. I was wondering, if I go to a stronger LED Q panel, is the distance more critical? In other words since I’m growing now at @ -12” space from the canopy, no problems in late flowering stage, does that add up to the same DLI if I spent the $ on a more powerful light fixture? I mean, it seems to me that in a 20”x36” tent a 300w LED Q panel would do well but I’d have to keep it up farther away. It seems to me, that learning to adjust the height of a slightly weaker light (2-200w Q panels) would accomplish much the same thing with a bit more attention on my part. Am I wrong? Any input would be helpful and interesting.

 

[RomanFilipowicz]

[TD="width: 433"]No, you are not. In the vegetative stage, LED grow lights should be between 12-24 inches away from the top of the canopy. During this stage, more light is needed for photosynthesis, so the light source should be located closer to the plants[/TD]

 

[GuitboxTom]

BU2B , I just found out, with the Hydra 1000, the change from 12” up to 14” only reduces ppfd from 1000s - 800s BUT, the periphery gains in intensity from @300- 400s up to the 600-700 range. So back up to @14”. Because I spread out the main colas to the periphery where She can use more light not less. It is a balancing act that seems to be less a problem with higher intensity fixtures over all.
I’m currently waiting for Apple to allow me to reset my password so I can purchase (from them), a light meter app, Photone or something like that. It looks to be fairly good and accurate.

 

[gbauto]

I run my QB-style panels @ 18-20" above the canopy.
That will usually give me a spot ppfd around 900 in the center of the canopy when run at 30-35 watts/ sq ft(480 w in a 4x4).
That's what I run in flower. In veg, I keep the same hanging height but run @ 50% power.

 

[GuitboxTom]

Update; 11weeks and 4 days into flower chopped the (smaller one on the right) Black Sugar. Letting the CBD C+C go one or 2 days more due to new pistils on fox tailing growth. She shows a few amber trichomes down lower but the new growth is @1/2 clear yet. I’m not sure if the fox tailing is due to lowering the lights to -12 inches or lights on all night and 89F. one night at @ 4 weeks into flowering. My playing with light distance didn’t help, I’m sure of that.