Quote Originally Posted by khyberkitsune
PROTIP: ALMOST NO LED MANUFACTURER CAN PROVIDE YOU THAT PHOTON FLUX DENSITY MEASUREMENT. Most of them aren't even aware that a proper measurement for photosynthetic photon flux density even exists.
It sounds like I need to get a "Quantum Sensor" or "Quantum Meter". I see they measure Photon Flux in the photosynthetic spectrum.

Does anybody use on of these currently? Are there any recommendations on brand etc... I found them starting at $140 on this site: Apogee Instruments Quantum Sensor - Measuring PPF