Technically speaking, pure citric acid does not contain salts.
However, it can chelate metal ions and in this way acts as a water softener. When it does this, it does not precipitate as readily as washing soda, but more readily than STPP.
However, it can chelate metal ions and in this way acts as a water softener. When it does this, it does not precipitate as readily as washing soda, but more readily than STPP.