I have planted my epi in cactus soil with lots of perlite and I got my first bloom this year after it had stayed outdoors. Previously it was just indoors and it just grew thin lanky leaves. I was told it liked full sun but my garden gets only part sun/part shade. But it still was able to make that bloom. I believe it was on its third year when it finally managed to make a bud.
So now I keep it outdoors all year long. It likes being pot bound, so you may want to make your container a little smaller. I think you can mix orchid bark with your cactus soil, it should help keep some moisture while allowing the soil to be porous enough. But give it as much sun as it can get. I find my plant thirsty, so I water it a lot especially now that we have heat wave going on in here.
