Aragonite sands (such as Caribe Sea) are coraline sands which do a great job of buffering alkalinity, and maintaining pH, and they can be a bit on the expensive side.
If the alkalinity of your tap water is low, this might be a positive thing, although if you are trying to keep your tank water less mineral enriched, maybe not.
Play, or pool filter sands are generally inert chemically and don't have the samp pH raising properties. I use pool filter sand for cichlids in many cases, unless I want the buffering qualities of aragonite. And it is inexpensive, I can usually pick up 50lbs for around $5.00.