Need advice for my Phal with rotten roots, pls.
 

Hello:waving, I'm a new member, so hello again. So, I have this phal flowering beautifully since November last year and still is in bloom with two spikes full of flowers. However, she had very nice healthy roots when I got her, but I have decided to repot it because the medium was breaking down. So I did put her into mix of fresh spag moss and orchid bark. And I have noticed today roots are getting mushy and rotten. So, I have only few good roots left, however the whole plant is very good condition. Her leaves are very firm and stiff, very green, there is also a new leaf coming out. Flowers are very nice looking, but now I'm afraid I will loose this phal, as I have some already. So I really do not know when and how I made a mistake of overwatering. Any suggestion for rescuing her when she is still in very good condition.

Personally I don't like sphagnum moss anywhere near a phal. I like mine potted in coarse fir bark and nothing else. I water at most twice a week in full summer, once in winter, and never let them sit in water.
Repotting in bloom is risky, but it may be your only hope, if the roots are badly damaged. In your shoes I'd strip out the sphagnum, carefully repot in a pot large enough to let the roots stretch out, and then leave it a couple of days without water in the hope of getting any damaged roots to heal. Then, I'd water sparingly once a week. I wouldn't water any more than that as I would want the roots to start growing to suit that medium and that watering regime.

The caveat being that that is what works here for me.

:welcomeflowers:

You may want to read at least the first few - several pages of this thread http://www.orchidboard.com/community...ends-here.html

I like using bamboo kabob skewers to determine when to water (google "skewer method orchids") - for Phals I water when the skewer is only slightly cool feeling to my skin). Also, Phal roots usually 'green-up' with watering. If potted in a clear pot, you can judge when to water by the color of the roots (if there are good roots visible). Don't water until they look whitish/silverish/cream colored.

Root issue is so common with phals it seems.
You mentioned the previous media being bad.
When you took your phal out, did the roots look fine?
If yes, then I find it strange that only your repotting made the roots rot.
Is it in clear plastic pot so you can see what's going on with roots, or are you taking the plant out and check every so often? This is not good for the plant.

How often do you water your phal?
How much of the roots are gone? more than half?
How do the roots look?