A basic light distance question

[SHRED]

As long as I am maintaining the proper DLI does it matter how far away the light is?

 

[Cobstopper]

Not at all. I hang my light higher and run it higher during the winter. I do the opposite during the late summer.

 

[Cobstopper]

This works well to help keep optimum temps in the tent.

 

[SHRED]

This works well to help keep optimum temps in the tent.

Main reason for doing this is my lights were 9 in from the tops and I didn't like the leaf temperatures.

I moved it up 16 in away and increased the light intensity a click to compensate. Thanks

 

[JP1]

You'll get better light penetration the farther you can keep the light away as long as you can still hit your dli

 

[SHRED]

You'll get better light penetration the farther you can keep the light away as long as you can still hit your dli

Thank you.
I went from 9 to 16 in. It's as far as my light can go up but I should be okay because they've stopped stretching at about 40 in tall.
I wish I had a infinite variable dimmer but I had to go up one click.
The tip top buds 49 DLI.
43 days.
Mephisto Genetics

 

[Delps8]

As hang height increases, the PPFD map will tend to even out.

Re. penetration - the further the light is from the canopy, the more photons are absorbed by the intervening air which means there are fewer photons. A photon has a fixed amount of energy, regardless of the distance from the source.

49DLI - I'd love to see grow lights replace the "Dimmer switch" with a label that reads "crop size".

Cannabis loves light. I get my plants to the 1k mark by week ~5 and I grow them through to harvest at 70-80 mols.

There's no need to grow them at that light level, of course, since cannabis will grow at PPFD's between ~70µmol and 1800µmol in ambient CO2 but, since modern LED will generate high light levels, getting more cannabis can be as easy as turning up the dial.

 

[Cannaficionado]

A lot of growers run their light at 80-100% and keep their lights at the max hang height and just let the plant reach for the desired light levels. This can cause leggy seedlings so until they kick off into full veg I keep my light closer, then raise it up after the 3rd node forms and bump it up to 100, but as long as you're maintaining a proper dli there shouldn't be much to worry about. Like others said you get deeper penetration keeping your light further away. Had more space to bounce around the tent to get to the lower branches, but thats if you dont have your tent stuffed edge to edge.

 

[SHRED]

A lot of growers run their light at 80-100% and keep their lights at the max hang height and just let the plant reach for the desired light levels. This can cause leggy seedlings so until they kick off into full veg I keep my light closer, then raise it up after the 3rd node forms and bump it up to 100, but as long as you're maintaining a proper dli there shouldn't be much to worry about. Like others said you get deeper penetration keeping your light further away. Had more space to bounce around the tent to get to the lower branches, but thats if you dont have your tent stuffed edge to edge.

I just measured this morning and they have stopped stretching at 40 in.

And I have an extra tall gorilla tent but I'm glad they stopped.

 

[Olderfart]

I just measured this morning and they have stopped stretching at 40 in.

And I have an extra tall gorilla tent but I'm glad they stopped.

Sounds like you have it sorted for now. For future reference, if you can get the DLI you want with the lights further away, you will get more light lower into the canopy than you would with the same DLI from closer lights. Call it penetration if you like, but the reason is that light intensity drops quickly with distance from the light, and the proportional drop over the depth of the canopy is lower with light further away.

For illustration, assume that the canopy is one meter deep, and the light positioned one meter from the canopy top. So, the bottom of the canopy is twice the distance that the top is from the light. Ignoring reflective walls for the moment, the light intensity at the bottom of the canopy would be .25 DLI. If, by comparison, the light was two meters away with the same top canopy DLI, the lower canopy would only be 30% further away, which would mean ~.6 DLI, about twice the intensity as with the closer light. The end point, for illustration, is that there is zero difference between the top and the bottom of the canopy in sunlight. (we are not talking about shade here, just light intensity absent shading effects).