Shell dwellers will like the sand much better from what I have read and heard from people that raise these fish,currently in the proccess of getting some multies myself.I used pool filtersand from home depot it is a little bit coarses than play sand and a little darker I think, just make sure you clean it before you put it in your tank.it took me about 30 minuets to do it,no big deal and I really like the way it looks. The guy that I am going to get the multies from said that the only real problem with sand and shellies is they can figure out what the filter does and scoop up sand and spit it into the intake tube like it is a "blackhole" lol so a filter of some type on the end of it is recomended if yours is closer to the bottem of the tank.gl you could add some crushed coral over the top of the sand .