Most of us use plain, unscented, generic bleach for chlorination. It only adds chlorine and a little bit of salt water to the pool, as opposed to the other forms of chlorine that all add something different (dichlor and trichlor drive pH down, add C YA, cal-hypo adds calcium, etc). Some states sell carboys of liquid chlorine, which is the same thing as bleach, only in twice the strength but much cheaper.

Janet