Grout Color For Pebble Shower Floor . How to install river rock shower floors. If you have plans to install a pebble floor in. White Pebble Tile White pebbles, Pebble shower floor and Pebble tiles from www.pinterest.com Clean up and remove any excess grout on your walls or floor. Reverse the classic with black subway tile and white grout. This can be done with a good quality penetrating sealer.