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Cob growers what's the optimal square foot coverage say for a 4x4 area Per 100w cob or what ever is the highest rated wattage cob.

I'm running 1000w cmh lights but want to start tinkering around with DIY cobs.
 
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The 12 cob 50/watt per cob is doing pretty good for me 600 watts at the wall. It was a rapid led kit, but all the parts are available through sourcing. If these were driven to 100/watts each, it'd blow up keeping a lid on heat production. imho. This was back a few months, but shows the fixture...
PB090003_edited-1.JPG
 
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I'm not worried about the heat with 5 tones of mini split AC at my disposal. I would be if I was still running DE hps bulbs though.

Also I need to State I grow large trees (8-9 week veg) so penetration is a must for the canopy.
 

CrimsonEcho

Self-Proclaimed Don Quixote
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I'm not worried about the heat with 5 tones of mini split AC at my disposal. I would be if I was still running DE hps bulbs though.

Also I need to State I grow large trees (8-9 week veg) so penetration is a must for the canopy.
50w/sf is a good wattage for leds. If your plants are too tall and you’re worried about penetration then build something with many diodes to provide mutiple sources of light and utilize lenses. Like 60-90 degree lenses.

Now i don’t see a need to go over 50w personally but if doing commercial and trying to get a little boost why not shoot for 60-65 or better yet 50w of white with 10w red which would give you fatter buds overall.

You can burn plants with leds, be aware. So i wouldn’t jump to 100w/sf. I’m growing only for myself and don’t provide co2 or anything but still that much light with lenses would fry the plants for sure.

I’m in a 3x4-4x4 area with 350-500w of leds depending on the phase they are in. I’m also growing tomatoes now under 350 with a shit ton of other things they all seem more than happy.
 
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So one 100w cob would cover 2 square feet with 90 dgree Lenses @ what hight from the plant canopy?

So it's looking like 600 watts will cover a 4x4 area for tree like plants
 
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Here is my 12 plant 6 1000w cmh lights each turned down to 860w. I should have lowered the hoods closer to the plants but I didn't know how much cooler the lights were compared to the DE HPS bulbs i was running.
 
I use 8 Vero 29 pulling 1000w from the outlet over 4 plants that are occupying about 16-20sqft at the moment, vegged an extra week or two, currently in week 3 flower. Going to add another 400-600 watts, heat is not an issue.
 
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If you have such a dense canopy like on the picture I don't think you'll need to worry about lenses and penetration. You'll get good penetration from the multiple lightsources without lenses shining at flat angles through the canopy.
I worried about the same points you do and thought I might need lenses, interlight or change to scroging. But I was surprised when I saw the first led run, and that was with cobs at very low wattage. Branches grew much stronger than with less more intense lightsources and at least as far down as before.

I'd try with bare cobs first, the more the better, and add strips for interlighting or play with lenses only if necessary. Or try to add lenses only to ¼ of your cobs to compare. Good lenses or reflectors aren't that cheap, so I wouldn't want to risk ending up with a lot of expensive lenses i don't need.
And you won't lose much, cause if it's perfect with lenses it'll still be really good without!
 
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