I was just trying to keep everything simple, Rick. Nothing I do is "scientifically" important/provable. I'm only a hobbyist grower, experimenting as I go along. I do have a reliable lumen meter, so measuring the light output at different distances from my fluorescent lights is quite easy.
The important thing I wanted people to understand is that the HO fixtures, though certainly more expensive, are far brighter. A down-side is that they also get hot, so plants have to kept a fair distance from them. During winter, that heat generated is a plus though. It helps keep the greenhouses warmer, reducing the power necessary to run electric heaters.
