Hi, I moved the question to General Orchid Culture. We use coconut husk chips with our orchid mix. I like it because it holds water well and we get the large chunks so that it takes up space in the pot but leaves lots of air room. This stuff does break down and you will have to repot eventually, but it is worth it. If you do use it, be sure to soak it to remove the salts. Many times the coconut chips we get have been washed in seawater and contain salts that must be removed before we can use it in our potting mix.
Cheers,
BD