Help Saving a Phalaenopsis Orchid with severe root rot
I received a phalaenopsis orchid from a neighbor. She had potted it in a ceramic pot with a single drainage hole drilled in the bottom. She said she repotted it in a potting medium labeled "orchid mix". It had no aerial roots when I received it. And because I was very busy when I received it, I didn't get around to getting repotting supplies for a few weeks after that. When I received it, there were bark chips in the potting medium, but it looked liked there was an awful lot of soil, too. There was also dry soil in the crown of the plant.
I went to an orchid nursery near me, got Orchiata bark chips and sphagnum moss and some clear plastic ventilated orchid pots, and got some advice as well. They told me to repot in sphagnum moss, don't spray the roots with hydrogen peroxide unless I see pests, and don't cut off any roots that don't pull off easily.
I didn't know how bad it was until I un-potted it yesterday. All the roots were rotted. I didn't cut them off because there would have been nothing left. I soaked the roots to get the soil off. I put it in pre-moistened sphagnum moss. I called the orchid nursery and told them about the complete root rot, and they said it's probably going to die, but the sphagnum moss and some fertilizer will give it the best chances of surviving. I have heard you shouldn't fertilize a sick plant; is this true?
Will the inner roots still absorb water and nutrients even when the protective velamen is rotting away? Is there any point in getting some disinfectant root wash (physan 20?), or is it a lost cause? Is there anything I can do to improve its chances of growing some new roots?
Thanks in advance!