Play sand - a definite NO ! it's asking for trouble.
Pool filter sand - Definitely YES - If you get it from a big box store, as opposed to a pool & spa supply outlet, ensure it's true pool filter sand - usually quartz-based silica - and get 18- to 20 gauge density if available.
I've used play sand for my kids of play with - I wouldn't put it in the fish tank without extensive washing. I use aquaquartz pool filter sand from canadian tire - The grains are nice and rounded which I like for my bottom dwellers - I can put it in the tank with no rinsing, and it doesn't cloud at all.