PFS is really great to work with in terms of convenience, but something I discovered by using it is that (white sand + dark poop = ugly tank). You really gotta keep on top of vacuuming the tank, and if you have really *anything* that is a bottom dweller, inevitably poop gets mixed in throughout the first half-inch or so of sand depth.
I have one tank in that situation right now and I hate it.
If I had it to do over again, I'd use a dark colored sand (like Tahitian Moon Sand), which is what I did in tank #3 and am much happier with the result.