At this moment in time, all of my tanks have sea sand that I've collected, or a substrate mix with sea sand. It's a brilliant substrate, but requires special precautions.
For one, some countries require that the collector has permits before any sand is collected - this applies to rocks too in some cases. Be sure to check up on this before you get into any trouble.
Secondly, try to find out how polluted the area is before you collect. If the water in the area is bad, collect elsewhere or if this is not possible, further up the beach and away from the water, even where the high tide doesn't reach. It's worthwhile getting the cleanest sand possible.
When washing, run tap water through the sand, stirring it while doing so. This is to get the fine sediment and other unwanted extras out of the sand, which will flow out with the water. Then soak the sand in very hot or boiled water to kill off anything extra. You can repeat these processes as many times as you feel is required.
Some people also allow the sand to dry in the sun for a day or so. I don't always do this.
Give it a try, lots of fish love it.
