Just out of curiosity why do people rely on lux readings for determining proper light intensity for LED/T5/MH etc??? I can put a high pressure sodium bulb for a parking lot light or a film/photo spotlight over my aquarium and make 80,000 lux easy.... but my corals would be toast by the end of the week. I think the key to success with any light source comes down to providing a quality of light with the right spectrum, coverage, and intensity for the corals. I agree that playing with spectrum and intensity to "match our eyes" is where a lot of the difficulty lies as our eyes are horrible calibration tools and on top of that everyone's eyes perceive things differently.