All orchids respond extremely well to hydroponic growth. Expanded clay pellets are used to absorb water from a saucer under the pot up to the roots of the plant. It is especially recommended for Orchids that require to be keep slightly moist such as Lady Slippers and Phalaenopsis. It is so light that it floats.
The pellets are only capable of holding 8% water. You do not have to worry about over watering . If you keep the saucer fill then you will not under water. Keeping a constant supply of water available for the roots will allow the plant to absorb all it needs.