Hydroton is a expanded clay which is both inert, but able to wick water from a reservoir. It allows for more air circulation and more consistent moisture to the roots of the plant. Orchid growers moved from "orchid bark" to Hydroton Semi-Hydro years ago, and I am trying it out with some of my plants, some which have given me a very hard time growing in modified potting soils.
Tonight I took cuttings I received in the late summer of Rhipsalis elliptica, micrantha, occidentalis and an unidentified plant from their small pots where most had some rooting going on. I removed them from their pot and got the majority of the dirt off the roots, then I soaked them for a few minutes and cleaned more of the organics from the roots. Hydroton should be soaked 4 hours or more before using. I then replanted the plant in this material. I moved my plants back to where they were resting and watered them with a weak solution of Dyna-Grow Bloom fertilizer, filling the saucer with the solution, which will keep the Hydroton moist.
There is a bible to semi-hydro on the web at http://www.firstrays.com/hydro.htm . I am not interested in the dogma of the side draining pot in most applications, the saucer will do fine. With my epiphyllums, I intend to use a similar pot, probably homemade to avoid a saucer on a hanging plant that is outside 60% of the year. I need something that is easy to hang first.
Semi-hydro has been used with many species of plants which are listed at firstrays.com. Try it and see how it works for you. Hydroton is available at your local hydro shop, the prime agra touted on First Rays is exclusively sold by them, and I don't want to have little clay balls mailed to me these days.