Yellowing leaves on Phals

[alannanoelle]

I have 3 out of my 4 phals with yellowing leaves right now! As far as I know, an old leaf will often die when a new one grows, is that correct? This first one has just started growing a new leaf, so I am not too worried about it.


This second one is the one I just posted about below regarding the new growth on the stem. It has not grown any new leaves since I adopted the plant.


This last one is my 3' + tall Phal. It is still in bloom, and the last bud just opened. It has not grown any new leaves since I have had it either.



As far as you can tell, are they all okay? Should I be concerned that I am losing so many leaves? The last one already lost a tiny, old leaf about a week ago, and the second one lost another leaf about a month ago.

Thanks for your advice!