Like the noob I am, I got the larger rock/gravel you get in bags at your local pet shops to use as the bottom substrate. What kind of sand/gravel do you get and where do you normally find it? I cannot find anything in any of the pet shops. Would like something to put in half the tank, so that the loaches would be able to dig through without hurting themselves, but not have to completely redo the tank lol. In middle of cycling it for first time, so not gonna worry about bothering the fish, as there is only 1 lonely Tiger Barb.. who hates all other fish but him.