Water that has been dechlorinated and prepared with a salt mix recommended for use in an aquarium. NOT Table salt. Table salt contains [i]man-made iodine[/i] which is toxic to hermit crabs. Natural iodine from sea water is not. In fact, natural iodine (which can be found at it's highest natural concentration in seaweed) is essential for successful molts and the overall health of your crab.
Water containing relatively high concentration of salt, usually over 1,000 ppm or mg/L but less than the sea. The ocean has about 35,000 ppm of TDS.
The general term for all water over 1,000 ppm (mg/L) total dissolved solids. Fresh Water - Brackish - 1,000-5,000 TDS Highly Brackish - 5,000-15,000 TDS Saline - 15,000-30,000 TDS Sea Water - 30,000-40,000 TDS Brine - 40,000-300,000+ TDS