I think some folks are really missing out how UN-messy Coconut really is.

The key is water, which is a huge bonus because it helps control humidity.
Or maybe one of the keys is the clay balls which goes underneath first to hold water.

When you use water and/or mist, you get a hard base like wet sand instead of dry messy sand.

And as as far changing the water bowl: if it is a decorative one that you have molded into the coconut husk, just take a qt of water and hold it 6 inches or so above and splash/rinse it in. So what if water overflows, that's the point!

Another huge bonus is No mold! Unlike Aspen.