Sounds like what happened to me. I purchased a baby phal too about two weeks ago. And the moss got me suspicious so I pulled up the baby to check the roots. And yes, the are on the verge to rot. That's why I do not like moss
I did remove the black tip of the roots and then re-potted it in a fresh charcoal and coconut husk medium (in a clay pot) And yes, there's an improvement as I saw a young root (that greeny lump thing), I think it does really well.
I water my plants (both phal and dendro babies) everyday as I live in a tropical country and it's very hot here. The medium will be dried in just a few hours
Oh, we Indonesians, water our plants with the rice water. If we cook the rice, we save the rinsing water for the orchid (not only rice, but also fish, or meat). It makes the plant grow vigorously with big fat green stem/leaves. And my mom's orchid rebloomed about 3 times a year.
