Careful here. I used to use South Down. It was a play sand you could find at hardware stores about 10 years ago. It was real popular in the reef community because it was low on silicates and did not tend to cause algae problems over time. Most of the brands now on the market are loaded with some nasty stuff that rears its ugly head after being in your tank for 6 months.....especially in a reef tank with higher lighting needs. Even if you wash junk sand, it will still leach undesirable elements into the water that can be problematic. It might be worthwhile to look into some of Caribbean Sands meant for our hobby. Saving a dollar now can cost you in the long run. And believe you me, tearing up an established sand bed once you realize it is the cause of your never ending algae blooms is a miserable process.
where's me money