I have a large Phal. collection, grown under lights and windowsill. Some of the plants have developed yellow/white spots. They are not mushy or soft then turn dry and brown. Doesn't seem to affect the flowering but very unsightly. I use spring water with small added fertilizer because water source from house is softened. Wish someone could give advice. Thanks.
It could also be a nutrient imbalance. How do you fertilize your orchids? Do you use any chemicals on your orchids? Around your orchids? Sometimes even salts from the fertilizer can lead the tips of leaves browning. A picture will help greatly.