Browning and blackening of leaves

[Zoren]

:: Good day members, it's been awhile since I visited the Board, I will try to keep better contact.
Now the problem at hand, I've been having browning and blackening of a number of my plants. The problem is not restricted to any one type of plant, it is happening to my Maxillaria, Paphs, Phrags and 2 of my Zygos. Not all my plants are having this problem (I have about 85 plants). I've moved them around my Florida room thinking maybe there might be to much or to little light. I would appreciate if one of my esteemed members could give me some suggestions or know what is wrong. See attached pictures. Waiting for an answer, Zoren......