Well, I think there was a thread about many different kinds of substrate, not just sand.
Sand (any sort) does not hold nutrients for the plants.
Fine sand or blended particle sizes tends to pack down, and the fine particles can drift up into the water and cloud it. Play sand is often like this.
Sand that has been sieved so the particles are pretty much all one size are less messy and allow better water movement through the substrate, and do not pack down. Pretty much all the sand and finest gravel sold in aquarium stores is like this. Of the non-aquarium sands some are like this, and are worth looking for.
Pool filter sand is one such good item. It is a local product, so varies in color. Local PFS in my area is off white with black specks. Usually this sand is graded to 30 mesh, or 30 grains per inch. Very close to 1 mm diameter.
Lapis Lustre is a large company and sells many different sized sands in bags, often available in rock or masonry yards. One of their products is actually called 'Aquarium sand'. That one is pretty coarse.
Blasting sand is the material used in sand blasting, and is another sand that has been graded so it is all one size.
A swimming pool material, not called sand, is a decorative quartz that is added to the interior finish and makes the walls of the pool different colors. An old product like this is Colorquartz, originally made by 3M. They do not make it any more, but similar material is still available. Talk to a pool contractor to find out more.
Sand is most often a silica type of material. This is neutral, has no effect on the water chemistry.
It is also possible to get material that is sand-like particle sizes, but will add minerals to the water. This is great if you want to keep hard water fish like most live bearers or Rift Lake Cichlids. Not great if you want to keep soft water fish.
Coral sand, oyster shell grit and limestone based sands are like this.