Ahh thank you i knew what RO /DI was i get that from my LFSASW is (should be) basically good quality RO or RODI water and a quality salt mix.
NSW is pumped from the ocean, river, etc.
RO = Reverse Osmosis
RODI = Reverse Omosis De Ionised
http://thereefuge.com/threads/what-is-rodi-water-and-why-do-i-need-it.2014/