I am thinking of adding gravel to my currently bare-bottom betta tank. I can't find any gravel at aquarium shops that I like (it's either too small, too rough, or it's coloured pebbles), but a hardware chain sells these pebbles which they say are fish-safe: http://www.bunnings.com.au/-tuscan-path-5kg-9-12mm-cream-pebbles_p3464249 (They have others that they specifically say are not fish-safe, which leads me to believe they aren't randomly lying.) I have a few questions about gravel: 1. Does the above look safe? 2. How do I prepare it to add to the tank? 3. I have some nice pebbles I've found in rockpools and would also like to add, but my mum has been using some of them with candles and they might have wax on them. Is there any way to make them fish-safe again? Thanks!