Nice tank, but looks too evenly spaced. Im with gf on this one, you should randomize it more and try putting some stones near eachother and maybe even one of the tree roots too.
It is Chiclid sand i got from my LFS.
It comes in 20 lb plastic bags with water & bacteria already in the mix
Costs about $24/bag and it took 6bags to cover the bottom of the tank.