Discoloration and pitting on phal
 

I noticed this discoloration and pitting on my phal this morning. Will be very grateful for suggestions.

I have seen this on Phals in the past but have never been quite certain what causes it. Have you checked for snails, spider mites or any other pests? Are the roots healthy?

Hopefully someone else will be able to help you. Good luck with it!

That looks like mesophyll collapse, which is often associated with watering with cold water, and allowing it to come into contact with the leaves.

I had something similar some years ago, and it turned out to be mites. Wiping down both sides of the leaves with rubbing alcohol should kill the mites, if indeed that was the problem.