Please review my phalaenopsis growing conditions! Root Stimulation?

[yolomanolo]

Hello everyone. Please give me your critiques on my Phalaenopsis growing conditions. Three novelty phals. One on each tier of a three tier corner stand. Under a 160 watt, wide spectrum orchid light. Little humidity and little air flow (central Arizona). All three in a bark mix, with lumps of sphagnum moss mixed in. Watered about every other week, (moss holds a good amount of water) fertilized every other watering. Only one in spike.
Two of them have very little roots because of root rot early on, so if anyone also has advice on how to stimulate root growth that would help. Please give me as much advice as you can. Everyone is welcome. Thanks!