As I stated I would want to kill any bad things in the sand,boiling,or boiling under pressure will do that.Also as I stated I am AT the beach every weekend anyway,so it's not an "out of the way" trip.For my current tank I bought 60 pounds of aragonite,and some arag-alive and I love it.
I also stated I am going to be doing an experimental tank.I want to try things that have me wondering.As far as pollutants,I am sure after the tank has cycled and or a bunch of water changes,It will be fine.Anyway,we can test for most of these things,mercury,iron,copper,sulfates,phos......