Phalaenopsis problems, I needhelp

[lindasbabies]

I posted this in the newbie section but guess I should have posted it here. I’m new to orchids and brand new to this forum. I have 2 Phalaenopsis orchids, one a year old and the other I’ve had for a couple months. I just learned that they came in the wrong potting media and that I should repot them. A month ago I potted them in bark and a tiny bit of sphagnum moss from Lowe’s. Then I learned that a different mix was better so I repotted again in this new media that I got from repotme. The phal I’ve had for a year was potted originally in sphagnum moss only and had root rot. The new phal was potted in a dirt like spongy stuff but was healthy. They both now have root rot and have lost most of their roots, their stalks have dark spots on them and the older phal has yellow spots under its leaves and the leaves are somewhat curling and the new phal has tiny black spots under its leaves. The aerial roots on both plants have cracks in them. What am I doing wrong? As far as watering, I only water when the media feels dry. Please help