Repotting in s/h during the winter is almost always problematic when it comes to phals. If you try it in the summer, the results are unbelievable!!
However since you went for s/h, you should expect stagnant growth during the forthcoming 2 months of winter. Keep an eye out for root growth in the upper stalk of the phal. I found that the s/h works better (ie less rot) when using normal pots and gradually increase the level of moisture at first with a deep dish under the pot. After it has become accustomed to the excess moisture you can keep the phal in a pot with a water reservoir.
You can fight mold without chemicals. Just decrease the amount of the reservoir or even better, don't keep it filled with water and only water the phal when necessary (when the pellets change color).
In my experience, moving a weakened phal to s/h in the winter is not a good idea. I have switched a robust phal to s/h during the winter, but it didn't lose any roots, however it sulked for months until spring/summer.