Phals developing pale yellow mottling
 

Hello, I am newer to orchids. One of my phals, about 3 yrs old, is developing pale yellow green diffuse spots on part of the leaves. The leaves seem a bit droppier to me. It is currently flowering. I water once a week w/ distilled water & small amount of orchid food, as I have always done. It is in bark. Any ideas? thank-you!

Is it the bottom leaf or bottom two leaves? If so, they go through a normal process of shedding 1-2 leaves per year - sounds like it could be this typical process. If it isn't the bottom leaves we need to look at other issues - pests or failing roots - when was the last time you lifted the plant out of the media and gave the root structure a good investigation?

Right now, most of what we can tell you is guesses. Could you post some photos please? :) Seeing it will help pinpoint the problem a bit better.

As those two already mentioned a photo will help, but even then it will be hard to know for sure.

I would think it would be one of: nutrient deficiency, stress, or cymbidium mosaic virus.

Distilled water and orchid food might not be giving it certain micronutrients like calcium that is often left out of normal orchid foods. If you're using distilled water then you would be better off using a proper 'hydroponic' food that has a greater spread of micronutrients designed for distilled water.

But i'm probably jumping the gun. A photo would be great!

Thanks for all the help!
 

I really appreciate the info & suggestions. I will try & post a picture-have to get my son to help me!
Maybe it is the water. I work at a dialysis unit (thats where my orchids are) & I have been giving them reverse osmosis water- there not minerals in it at all, its very pure. I will check out the special food mentioned (& post pictures!)
thanks again