Animal Care/Land hermit crab chlorine

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All water (H2O) for land hermit crabs must be free of any form of chlorine.

Water companies are increasingly using chloramine (NH2Cl) in tap water, rather than chlorine (actually hypochlorite - Cl2O2). The chlorine in chloramine will not "outgas" from water (dissipate into the air) with anywhere near the speed and reliability of the chlorine in hypochlorite. That is precisely the reason that chloramine is being used to protect human water supplies from bacteria.

When making plans to remove chloramine, note that unless

  • a gas is produced that bubbles out of the water or
  • a solid is formed that precipitates out of the water,

adding a product to water to "remove" something simply converts one compound into another compound, rather than actually removing anything from the water.

For instance, many products that "remove" chloramine will "add" ammonia. Choramine is created by combining chlorine and ammonia (NH3), so when the chlorine bond in choramine is broken, ammonia is leftover. Aged (weeks) choramine-treated water will contain this ammonia.

Sodium thiosulfate, Na2S2O3, is the primary ingredient of many commercial water dechlorinators. It releases harmless chloride ions from both hypochlorite and chloramine, but it also releases the ammonia from chloramine.

As a result, water+chloramine+sodium thiosulfate requires an additional chemical that converts the ammonia into a non-toxic form before the water can be given to hermit crabs. However, a sodium thiosulfate product may not contain that second chemical or even mention ammonia. This is a case of buyer beware!!

Other chemicals exist that will release chloride ions from chloramine and also convert the resulting ammonia into a non-toxic form. (See the "super 10-gal tank" setup.)