Instant Ocean Conversions Instant Ocean Dechlorinated Water 1 cup 2 gallons 1/2 cup 1 gallon 1/4 cup 1/2 gallon 2 tablespoons 1 quart(4 cups) 1 tablespoon 1 pint (2 cups) Some hermit crabs require salt water in addition to fresh dechlorinated water. Although Purple Pinchers do not require salt water in order to survive, they seem to like to drink salt water occasionally too. I've been using Instant Ocean aquarium salt successfully. There are other brands of aquarium salt available but they may have different instructions for mixing salt and water. Be sure to read the instructions on your box of aquarium salt carefully.