I am switching to sand in my tank, mainly for my Cories but also for a more natural look. I bought some Quickrete PFS at Home Depot. I really like the look - lots of fine grain, with flecks of larger white and orange pieces. My only concern is that the white pieces look kinda rough or sharp. Is there any reason I need to worry about this for the Cories? I would assume as many people talk about using PFS that this isn't a problem, but wanted to make sure I didn't need to be picking out the larger white pieces or something (which would take forever).