Hi, I haven't had experience yet with Brassias or Dendrobiums so I can't help you there, I'm sure someone will be along shortly to give you some sound advice. About your phal, you say the lower leaves keep shriveling and dying? How many leaves so far? I think it is a natural process for the lower leaves to fall off to make room for new ones eventually. If it appears there is no damage other than the lower leaves turning yellow and falling off, then it should be fine.