Lighting Cobs distance from plant canopy?

[Jibblerjoe]

Got 3 vero29 driven 2100mah. Cobs have no lens. What distance between light and canopy?

 

[BigSm0]

This is kind of like asking how much water should you add to a pot. There are a lot of variables and lots of info needed before anyone can really answer this. Strain, age, space, number of plants under the 3 light, light schedule, co2, reflectivity, and at best you would get a guess but until someone puts 100w cobs over the exact strain at the same exact age you will never really know. If I ran 100 watt cobs I’d probably start around 36”. The down side is you are getting the same ppfd at 36” as probably a 50 watt cob at 16”.

 

[Jim Ray]

Inverse square law for light applies. If you double the distance from light to plant canopy, you quadruple the power required. It is not linear.


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[Jibblerjoe]

2x4x5 tent, 3 plants, 8 wks on plants. Light on 20hrs a day, active cooled. After 18 hrs 1 og the plants get droopy, but after dark period it is back to perky. I have a dimmer switch. Running 75 to 80% power. No co2.

Would I be better off with light dimmed and lower to plants.
The cobs a 9.5 on center. @bigsmo

 

[BigSm0]

2x4x5 tent, 3 plants, 8 wks on plants. Light on 20hrs a day, active cooled. After 18 hrs 1 og the plants get droopy, but after dark period it is back to perky. I have a dimmer switch. Running 75 to 80% power. No co2. View attachment 823521 View attachment 823522
Would I be better off with light dimmed and lower to plants.
The cobs a 9.5 on center. @bigsmo

Sorry for the late reply. How’s the plant reacting to the distance you are at now? Are the short and fat or stretching a bit? You are better to keep the lights closer and dimmed as long as the coverage suits the space.

 

[Jibblerjoe]

Sorry for the late reply. How’s the plant reacting to the distance you are at now? Are the short and fat or stretching a bit? You are better to keep the lights closer and dimmed as long as the coverage suits the space.

I got it full power, at just over 2ft above plants. I finally got some praying leaves.