Modern leds and distance to plants

[tyke1973]

14/18 inch i have found best

 

[NoWaistedSpace]

Here is an example of photon counts at different heights.





This is why I stay 18 to 24" above and use the driver to control

 

[Veganfly]

Here is an example of photon counts at different heights.
View attachment 79068
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View attachment 79074
This is why I stay 18 to 24" above and use the driver to control

Thank you for the par charts, but why not dimm down the light instead of placing it higher?
We could obtain similar par readings of those at 18"/24", running the light at 50%/75% of its maximum power at 6"/12".
The main advantage would be a significant saving in consumed Watts.
Are there any cons to this approach?

 

[JohnFonda]

Thank you for the par charts, but why not dimm down the light instead of placing it higher?
We could obtain similar par readings of those at 18"/24", running the light at 50%/75% of its maximum power at 6"/12".
The main advantage would be a significant saving in consumed Watts.
Are there any cons to this approach?

Less angles of penetration and less coverage but running more diodes softer is the solution and works better imo.

 

[NoWaistedSpace]

Thank you for the par charts, but why not dimm down the light instead of placing it higher?
We could obtain similar par readings of those at 18"/24", running the light at 50%/75% of its maximum power at 6"/12".
The main advantage would be a significant saving in consumed Watts.
Are there any cons to this approach?

I was showing you the spread consistency. The closer you get, the less photons to the corners. At around 20" takes advantage of the photons.
I have to dim at 20". I run 16 Vero 29's in a 4 x 4 between 1050 and 1400mA and reach good PAR numbers. 33 watts or so a COB. So everything runs nice and cool.

 

[Veganfly]

Thanks for the replies.
Coverage is not a problem in my case tho, I just bought a big 8 bars fixture (optic slim 600h) that barely fits in a 4x4.
I'm still trying to figure where is the sweet spot for this beast to hang above the canopy

 

[JohnFonda]

Thanks for the replies.
Coverage is not a problem in my case tho, I just bought a big 8 bars fixture (optic slim 600h) that barely fits in a 4x4.
I'm still trying to figure where is the sweet spot for this beast to hang above the canopy

Keep it at 18-20 and adjust power through the run. That should be optimal. Idk how low it goes but it doesn't take very much at all for seedlings and early veg.

 

[NoWaistedSpace]

I start out about 36" and let them grow to it. The closer they get, the more compact the growth will get. And it's at the plants own pace. People blast way too much light at them to soon and stresses the plant. Just my personal observation after 5 years of messing with LEDs.

 

[Veganfly]

I start out about 36" and let them grow to it. The closer they get, the more compact the growth will get. And it's at the plants own pace. People blast way too much light at them to soon and stresses the plant. Just my personal observation after 5 years of messing with LEDs.

So from veg to harvest always at 36", but, do you change the power of the light during the growth and flowering, or do you keep the same intensity?

 

[NoWaistedSpace]

So from veg to harvest always at 36", but, do you change the power of the light during the growth and flowering, or do you keep the same intensity?

No, that's to harden the plants to the light intensity. That gives them a chance to adapt before you blast them with photons. I adjust the intensity with a PAR meter. I have a HydroFarm meter. You need one if you are DIY'ing so you can adjust spread and intensity at a certain desired height.
Kinda my rule of thumb is around 20 to 24" and adjust dimmer from there for PAR. You can drop your light to whatever height as long as you are in a decent PAR range. But you really don't know unless you are metered".