in my experience... i can't trust NSW... it carries pests, aside from being it a used water that carries more than the acceptable amount of nutrients. what i do is i buy salt mix, kahit mura lang... mix it with aged, and conditioned tap (thanks to sera aquatan). i test the water for any offs... sometimes i get low calcium. what i do is i just add calcium chloride, sodium bicarb, and sodium carb (10% of total amt of sodium bicarb), natural trace, red sea's calcium, strontium, iodine, molybdenum, and stress coat (API). so far.. everything's doing great in my DT.... obviously when using tap... you will be more concerned with the tds that raises the number of my brown algae... before it used to be like everywhere in my tank, until i discovered the power of ATS... minimum algae in DT (plus the turbo snails), more algae in ATS, 0 phospate, 10ppm nitrate. well that's how my tank goes... it might be good for my set up, but not for others...