LED grow light distance

that's an unsophisticated dumbed-own rule. e.g. a single point of light, a bulb, mas to stay further away than the same wattage light with better distributed diodes -- and this is ignoring the heat difference which also plays a role. Greater efficacy and better distirubtion of light allows better lights to get closer. Your environment will have an impact on how close you can get your light too. Higher humidity, while maintaining targetted VPD, will allow the light to be closer without damage, all other factors remaining the same. Quantum boards will need to be further away due to poor diode distribution compared to a frame with strips/bars of diodes spread out more. in the end it will take some trial and error no matter how accurate a suggestion is. How the plant grows should be used to choose the height, not some pre-ordained distance ignoring all the local variables. Also, UV being on all the time is useless. Even properly using UV may or may not help. it is a mostly untested hypothesis without a confident answer as of yet. One thing is for sure, uv diodes on all the time hitting the plant will be useless. the plant will develop a resistance to it long before it develops flowers/trichomes. it does not feed the plant. it is something that supposedly damages it and causes a reaction with a net benefit. No or very little trichomes production early on means no benefit. no biggie as long as it doesn't add too much to the cost of the light. it's just a gimmick. Assuming geomety of light distribution was part of the design process... 1870 umol/s can cover just over 23 sq ft and provide 860PPFD which over 12 hours is 37.2 DLI. 1950 / 80 = 24.375 sq ft, or roughly 1 more sq ft of coverage. this infor as well as a basic light metere - does not have to be a quantum meter - can help you pick out the best hanging distance with best resulting coverage wall-to-wall. Proportional intensity is your guide... the highest value in central area is "100%" and everyhing is relative to that... adjust to improve corners/edges relative percent to middle and don't sacrifice overall light hitting the canopy while doing so... if you raise it too high you lose DLI with great number of photons missing the plants or absorbed into walls. make sure average klux of measurments at different locations maintain overall average... a few more or less is no big deal, but lower averages should be avoided. again.. exactly how close will be dictated by the plants.. if the nodes are too tight, raise the light. if you are bleaching the tops of buds, raise the light... simple as that. you want it as close as possible that it doesnt cause damage and doesn't cause less than ideal growth in vege. i'm running a higher VPD than previous years. I can get my lights much closer this year without bleaching my colas. It wil not be exactly the same for every garden with that light because numerous variables are relevant to results seen.