BigO6687;4583932; said:none, you need untreated sodium, not table salt, most people use aquarium salt by api, including myself, but ive heard kosher salt and other pure salts (not table salt, which is NaCl) that are untreated work well
Dark Jester;4583949; said:What do you think 'salt' is? http://en.wikipedia.org/wiki/Sodium_chloride
Aquarium Salt, Rock Salt, Table Salt, Kosher Salt, Sea Salt, etc, etc, etc. Whatever you want to call it, salt is salt. There are different purities, grain size, and additives which can be present which cause the different names. It's all based on NaCl, Sodium Chloride.
The only risk with table salt, as I said previously, is that it may contain anti caking agents which can be toxic.
Dark Jester;4583907; said:Note: If using table salt, make sure it does not contain 'anti-caking agent' or 'yellow prussiate (of soda)'. That can be toxic.