The shell must not hold water. These are epiphytes and allowing them to sit in water will kill them quickly. This particular Dischidia also has a tendancy to rot so be carefuk watering it while it's cold. I have seen entire plants turn to mush overnight. In my opinion this is one of the hardest Dischidias to grow. Good luck.
The only moisture this gets is the very slight mist it gets when I'm moving the wand from one orchid to the next...barely anything but I will definitely keep an eye on it.