changfra for me i usually wash the sand with FW a few time den use warm or hot water to rinse the last time but from some books they suggest to boil the sand that for your info
as for Dazza i collecting the sand from the beach so far using it for my 2 4ft tank about 2" deep still ok just that it very heavy if no car , me taking bus so need to traval lot of time to get the depth of sand i wan