White spots/blister on Phal leave

[franfrancy]

Hello everybody!
I'm a beginner on orchid world and I need your help.
Days ago some spots appear on the leaves of my Phal. I use MSU fertilizer, weak solution, I water the plant around once a week, I put the orchid on the sink, flush with water and then apply the fertilizer. It's potted on a clear pot with bark mix(I got it from repotme).
Also the plant is located close to the north window, in a very bright room, but not on direct sun.
So far the plant seems doing good, new stem is growing and the roots are very healthy, but the spot worries me, I had searched around and I could identify what is the problem.
I'm sending some pics and thanks a lot for any help!
Ah, I forgot to mention. I live in Chicago.

[WhiteRabbit]

Sorry, I don't know what that might be from. Is the underside of the leaf affected?

[franfrancy]

Hi Sonya.....no, underside the leaf is normal. The plant seems to be fine but it worries if could become harmful

[NYCorchidman]

I don't think I see anything. Could you post a close-up picture showing the mentioned leaf??

Blisters on leaves could be a result of incorrect watering when cold weather persists. It is called edema. but without seeing pictures of your plant's symptoms, it is impossible to tell what it is.

[franfrancy]

Let me try to upload more pics. I tried before but didn't work.

[franfrancy]

I normally water it once a week, I look if the roots are kind of silver and then I water it.
I bring to the sink and flush with water and after apply apply the fertilizer.
Should I change the water method? Is the damage go away?

[NYCorchidman]

The way you water sounds perfect.

Do you water at night?

The symptom does look edema to me. and you mentioned it happened overnight, right?

Try warmer water or water during the day time if you water at night.

When too much water is absorbed during cool night, this thing happens I read.

[franfrancy]

Thanks NY
I dont water at night but sometimes in the afternoon and I use cold water.
Yes, it appears overnight and the leaf didn't get mushy. The orchid still healthy but now that you mentioned about the water, yesterday I notice a drop coming out of the stem, so I guess you are right.
Do you know if I adjust my water schedule the leaf will come back to normal?

[NYCorchidman]

No, edema (if it indeed is edema) does not go away, however, it does not harm the plant. It is just mainly aesthetic on the eyes of the beholder.

I would suggest that you water in the morning or midday rather than in the afternoon, and also, use room temperature water instead of cold water.
It can really hurt the roots and the plant tissues when you use cold water on tropical plants.

[franfrancy]

Thanks a lot NY!
I will pay more attention to my water methods
Have a great day!