Phals stressed from lack of water?

[Tee Dee]

I have become concerned that the leaves on my Phalaenopsis which were plump and smooth may be exhibiting signs of stress, possibly related to insificient water. The photo is of orchid which has highly developed evidence of ribbed and thinning leaves. Aside from this trait the orchid appears healthy in all other aspects. Three additional Phals may be in the initial stages of the same symptoms of stress.

I water 3 of 4 plants on the fifth day by submerging the roots and soaking the bark for 30-40 minutes. Using this schedule the media appears to dry within a couple days after watering. Humidity is maintained at 50-60% RH.

It is my intent to shorten the period between watering from 4 to 3 days. A larger, mature Phal is on a 5-6 day schedule because I am concerned the center of the pot remains constantly moist and will subsequently cause the roots to rot. I recently purchased a kitchen scale and will begin to monitor weight loss to help dial in watering schedule.