API Aquarium salt is indeed plain ordinary salt but without additives such as iodine or anti caking agents. It can be used to treat minor infections.
Colin suggested using plain salt, sodium chloride, in case your fish has a minor infection.
The salts in your link are for increasing GH, KH and pH and are used to make water hard enough for Rift Lake cichlids where RO is used or have soft tap water. If your water is already hard enough for your fish you don't need to add the salts in your link. But if your water is too soft for them, adding it would help - you would need a GH tester to work out how much to use to get the GH to the level needed by your fish.
Salt is a chemical term meaning the product of reacting an acid with a base. There are hundreds of salts. Common salt, sodium chloride, is just one of them.
Colin suggested using plain salt, sodium chloride, in case your fish has a minor infection.
The salts in your link are for increasing GH, KH and pH and are used to make water hard enough for Rift Lake cichlids where RO is used or have soft tap water. If your water is already hard enough for your fish you don't need to add the salts in your link. But if your water is too soft for them, adding it would help - you would need a GH tester to work out how much to use to get the GH to the level needed by your fish.
Salt is a chemical term meaning the product of reacting an acid with a base. There are hundreds of salts. Common salt, sodium chloride, is just one of them.