written by Jennifer Nielsen

Freshwater aquarium salt is not the same as marine or ocean salt
Freshwater aquarium salt is not the same as marine or ocean salt

The existence of an ocean water dish is a source of great controversy in the world of hermit crab owners. Why the importance of this type of water is rarely debated, it seems that the products used in the creation of Ocean Water are the source of much debate. Just as all hermit crab owners know not to use table salt for their crabs, there are two types of salt available for aquarium use. Fresh Saltwater as well as Ocean Water Salt, which although made of the same components have vastly different role within the world of fish keeping.

A saltwater dish is offered as a means for hermit crabs in captivity to gain access to the ocean with in the habitat. In the wild, a hermit crab would normally crawl down to the sea side to get sea water to help balance the ph/ion levels within their shells. However, in the man-created environment within the habitat, this cannot happen unless a human is providing this type of water. The product used to create this water is of critical importance for this reason, plus in case of injury, salt water is also naturally defecting that will assist in healing of wounds. Hermit Crabs have been known to be seen soaking an injured claw within the salt water pond. Also, molts tend to go a better in the habitats where salt water is readily available.

In order to understand the difference in the product lines, we need to see what Natural Sea Water (NSW) is composed of. The first ingredient is salt of course. However, it also contains about 70 other trace chemicals within it. So while the primary ingredient is in fact common salt (NaCl) there is also several other elements which are key to the composition of Ocean Water. The major components in addition to Chlorine and Sodium are Magnesium, Sulfur/Sulphur, Calcium, and Potassium. Also, common minor components are Bicarbonate, Bromine, Strontium and Silicon. These are considered to be essential to the creation of artificial salt water. This is in addition to other elements, which are in lower amount but found in NSW, such as Chromium, Cobalt, Copper, Fluorine/Fluoride, Iodine/Iodide, Iron, Manganese, Molybdenum, Nickel, Phosphorus/Phosphate, Selenium, Tin, Vanadium and Zinc. Also it is important to note that in the creation of artificial ocean water mixes also tend to be over in Nitrogen/Hydrogen, Nitrate-Nitrogen, Phosphorus as well as Silcon. So offering just one of these elements, such as just the salt, is not truly providing a Salt Water, for several ingredients are missing from the equation.

Now, this is not to say that the salinity level found around the world is stable. Factors such as weather, heat, and location are also factors in the composition of salt water. The Dead Sea is in fact the saltiest body of water in the world. Water located around the equator is also saltier than that which is found in the arctic. While this could be important to different varieties of Hermit Crabs, that is a subject for more research to find out which products mimic different water conditions world wide.

Ocean or Marine salt is required by hermit crabs
Ocean or Marine salt is required by hermit crabs

Freshwater Salt is designed to primarily be a treatment of illness in fish. Specifically, freshwater fish can tolerate low slowly introduced salt in their water. Natural Freshwater does contain salt, but compared to the amounts found in NSW water, the volume of this is significantly lower. Products designed with only this purpose in mind, tend to lack the other elements found in Sea Water. The same is true for cooking salt made from evaporated ocean water. For while the salt is sea salt, it is lacking the other components that make ocean water what it is.

Ocean Water salts, however, provide not only the salt needed but the other components as well. In fact, the label Ocean Water mixes might be a better term for these products because of the fact that they are not just containing one part of the water, but a variety of components that are found in NSW. For the Aquarist who keeps salt water tanks, this is of critical importance to their pets. Therefore, they tend to go with mixes that are more than just salt. In trying to offer Hermit Crabs ocean ponds, it is important that a mix with true composition closest to NSW is used which is why ocean water salt is preferred over Freshwater Salt.

Websites used to provide information in this article are:

Gore on Salinity
Dead Link-Page not Found See archive of webpage here.
Sea Salt mixes

Brands of salt to look for:

  1. Instant Ocean/Instant Ocean Reef Crystals
  2. Oceanic
  3. Red Sea Salt
  4. Fluval Sea Salt
  5. Coralife
  6. Tetra Marine