PhalPhal - I've decided that the problem is the tinting. My atrium has tinted skylights. Recently did readings standing in the direct path of the sun and the highest it got was 1000fc. 3" to either side is was like 300fc. (see my Masdevallia guidance or assitance Post)
Nevertheless, I have Phals, Oncs, Catts and more all thriving AND blooming. I've given up trying to figure it out. It works, the orchids are happy and I'm happier.
