NSW

Natural Seawater. 35 ppt salinity, ~6.5–7 dKH alkalinity, ~412 ppm Ca, ~1,280 ppm Mg (1,284 at 35 ppt).

The reef hobby uses NSW as the baseline. Most salt mixes target NSW or slightly elevated. Coral Pro and similar reef-elevated mixes aim above NSW.

Last reviewed 2026-09-30