Regarding heat sinks, @slain is right. I just dug a bunch of old CPU heat sinks out of my junk box and used them. Zip-tied them to the sides of the blurple so the air blows through.
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@cogitech just as comparison i was stating that 35-40w mark in reference to the bridgeluxs, now every light has its own efficiencies and your citizen cobs are in the 150lm/w range vs the bridgelux 180-190lm/w, also your burple is probably quite inefficient as @Foreigner mentioned, how much so no ideaâŚ
But something to also consider is the distance from plant to light, inverse square law and all even if thats all skewed when in a tent or enclosed space, so sometimes we see people running 80+w/sqft of good led but yet they are two to three feet away from there plants essentially wasting most of that energy,
So how far away are your lights from your plants ? and is the multi-strain CBD seed run thread your current one, as i havent read it yet but will tonightâŚ
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The plants are certainly getting all the light they need, and more. This is with just the bloom switch on the blurple.
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Yeah⌠alot of distance between plant and light thereâŚ
edit: ask @toastyjakes if light distance makes a difference
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I agree with Sparkle!
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just to preface say your in a completely open environment, every time you double your distance your actual light decreases by 4 times, but again we arenât in endlessly open environments so its not a hard fact per say but still comes into play
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I just moved them from about 14 inches up to about 22 inches, because I am worried the plants are light-stressed.
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Yes, thatâs my current run. The plants were doing really well (as you can see in that thread) but in the last week or so they have been giving me subtle signs that they are getting too much light.
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well the signs for too much light are obvious once you know of them, but what are you seeing and do you have any pictures ?
Also did some calculations and comparison for your space vs say one of mine, for you to be running the same amount of light if you were only using the cobs you would probably need to be in the 50w/sqft range, and have those lights alot closer, now im not saying the plants that currently are in there wont show some stress because of a change in light levels if the light was closer cause it is a change but guess we need to find your happy range 
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Very slight bleaching on the tops of a couple (the 2 on the right in the photo), plus tiny bits of browning on the very tips of the serrations on some. It isnât the typical look of nutrient burn, thatâs for sure, and it isnât a âproblemâ yet, but I am sensitive to whether my plants are 100% happy and they were telling me they werenât. I can take pics later. The shortest plant (therefore furthest from the lights) shows none of these signs.
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This where the point intensity of HID and COBâs can be net negative imho⌠i.e. they require a good amount of distance to avoid heat and burn issues etc in effect reducing the amount of light the plants get over all when compared to say strip/board lights. I moslty keep my lights within a couple of inches of the tops now without any problems, and even when something does reach them, there is no charring or burning etc, The peace of mind from knowing that my buds arenât at risk of immolating when I am out is a bonus. For a while I had a mix if cree cobs and strips, but the summer heat here just made strips less of an management issue, which of course is not the case for everyone.
When seriously under light and radiant heat stress the leaves will often canoe and curl up. Thatâs a pretty dead giveaway imho. Bleaching is an extreme form of stress⌠i.e to the point of parts of the plant dying. 
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well the bleaching is easy to tell once youâve seen it , for me the chlorophyll âretreatsâ more or less to leaves that are shaded by other leaves or by other plants, bulking up in the areas where they can take more advantage of the light cause direct is too much and that top layer act more like a sunshade than anything, have a picture or two of it somewhereâŚ
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I forgot to mention the canoeing, they are certainly doing that.
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So I was totally wrong on the distance. I just took this photo with the light at the position I raised it to when I got home tonight. It was a good 5-6 inches lower before. Also, the canoeing has already reduced from what it was. I guess the âtop downâ perspective made the light look considerably higher in the photo I posted earlier.
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Put that damn joint down and start paying attention !!!
LMAO!!!
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Ya no shit, eh?
I swear sometimes I feel like I am almost 50. I guess thatâs because I am.
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So⌠thanks for this.
Iâve been cooking some seedlings under 4 â100wâ SI LEDs with no fan. 
(6"min distance, 3sq. ft., panda film around a kitchen cart, no top)
Funny thing is: I measured the leaf temps & all were âhappyâ from 73-80 F so I presumed all was good.
But the plants are telling me the current set up is B 
S.
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To recap, I am pretty sure my lights were too close to the plants, combined with a bit too much intensity and I also think I wasnât getting quite enough water into them. Shutting off the veg switch on the blurple, raising the lights up, and giving them a good soak has changed things for the better very rapidly.
I have to thank everyone who offered so much valuable info in this thread, and I hope it helps some others who might stumble upon it in the future. The key is noticing the subtle hints that your plants give you that there is something they arenât liking. At least I got that part right.
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@cogitech do you have an IR/non-contact thermometer to take leaf temps?
@Mr.Sparkle howsabout you? you like to measure stuff, right? 
My suspicion is the surface temps are not âcellular tempsâ & itâs too rough of a tool. (?)
Just yanked a male out of there this a.m. & all the roots are happier than the plants. WTF.
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Yes, I do have one of those thermometers, but I donât use it very often because I have never found authoritative info on what ideal leaf temperatures are.
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