I have been growing my C. walkeriana in a plastic Vanda basket and red lava rock, with eggshells mixed in for extra calcium. I water it when I water my other Cattleyas which is typically twice a week during the winter and variable during the summer when they are outside. Currently it is under T5HO lights and, outside, it gets direct light in the morning and late afternoon.
I have not bloomed this one yet as it was a seedling but I am hoping for the first bloom in the next twelve months.