I have just recently set up a 30 gallon reef mostly composed of 5-6 month old rock and sand sitting in a bucket (had to move...now I got it set up agian).
Dont let anybody tell you its not good anymore!!!!! PLEASE...this stuff is as expensive as its gets! Just rinse out the sand, agian and agian until it comes clean, then use. Mine when i rinsed was dirty as could get but after rinsing agian and agian it came clean and I have no problems in my tank with it! BUT...The bacteria will be dead (of course...) so after it is clean and in your tank, seed it with sand from a friends tank with no real problems...and you should be good to go