kdt15 said: how can an LED design (using same, good lights) end up with vastly different yields, Click to expand...

kdt15 said: I mean a watt is a watt regardless of design right? Click to expand...

not all of them are good lightsno! or there would be no incentive to use one type of light over another. CFLs to the best LEDs span a huge range of photosynthetic efficiency, like 0.7-2.2 umol/Jthe following is worth a read despite the fact that the LEDs in that study were from 2013-2014 and most are sub-HPS in efficiency:once you get a handle of umol/J then you can make sense when an LED vendor quotes a umol/J or PPF (NOT PPFD!) numberumol/J = (PPF)/(input wattage)PPFD = spot measurement which by itself is useless (slightly more useful as a PAR map at a distance but still doesnt tell you overall efficiency)