Pebble shower floor

We are redoing our shower and are planning tile walls and a pebble-grout floor. Folks at the tile shop warned that the pebble floors were very prone to mildew. Any experience or ideas regarding this problem?
Thanks Jim

A couple of things: with tile, the recommended slope is 1/4" per foot, but with a pebble floor, you probably want to nearly double that to account for the potential high spots...you really want it to drain. Then, because there is a lot of grout, you might want to consider using a surface waterproofing membrane, either a fabric or paint on the setting bed to limit how far moisture can penetrate. It would be expensive, but you might consider using an epoxy grout, which is pretty much impervious, won't absorb moisture, and therefore doesn't support moisture. You might want to check out www.johnbridge.com for some thoughts as well.

ANY surface that can "trap" water will be prone to mildew, and I doubt that you will be able to construct the floor and NOT have low, or dammed up, points

Recently I renovate my bathroom and use river rock tiles for creating a pebble floor but I realize that the floor not cleaned out properly. Can anyone suggest me what should I do?