Here is a link to Dr Foster and Smith's substrate.
Fish & Aquarium Supplies: Marine Substrates, Sand, Crushed Coral, Live Sand
They have lots of options in terms of sand. What was stated above about live sand is pretty on point IMO
. If I was in your shoes, and I was just a couple of months ago with a new setup, I would lean towards the agragite sands to help buffer your pH. Not only that, they have natural colors like pink and black if you are looking for something different.
I currently have non-agragite crap from Petco in my 36 and am using aragamax in my 55. Not seeing much different besides the sand in my 55 being finer, which is better suited for sand sifters.