Hello, I am totally new to orchids.
I have a phalaenposis it grows medium light yellow flowers, there are two stems with say three flowers each & big thick green leaves at the base, as well as roots that grow out of the top of the pot. It is grown in moss and I have it placed on a tray of rocks to allow air flow.
I do not keep it in standing water, I water it through once a week and alt weeks with orchid flowering food.

OK so two problems:
1.The roots growing out of the top of the pot are shrivelling up, I thought this was due to under watering or lack of humidity so I increased the watering to every 4 days?
2. I have this past week had two flowers from the same stem completely wilt - one then a week later the next, so I cut them off. I took a look on the bottom of the pot and there seems to be a white film, not fibrous strands but more of a chalky film (no smell) on or around the root & moss nearest two of the drain holes?

Any ideas??