What salt do you use?

[Matt]

Originally Posted by rickjames

Not entirely true. IO is formulated to mix with an "average" amount of minerals in water (i.e. tap water). Kent and others are formulated to mix with RO/DI water.

If you mix IO with RO/DI water you end up with about 330 ppm calcium, depending on the specific gravity of the water, and a lower alkalinity.

Sources? The Aquarium Systems website suggests that it is Reef Crystals that is formulated for tapwater use. The infamous S-15 Report (which uses apparently valid analysis for the mixes, although the scoring system that the sponsor uses to determine what's "best" is completely subjective and self-serving), shows that IO, Kent and RC are all substantially similar, nothwithstanding the marketing data.