[MHGinTN]

Short term, use the bleach. Beyond six months use the water purification system.

[PA Engineer]

Short term, use the bleach. Beyond six months use the water purification system.

You can also use Calcium Hypochlorite to make bleach. It must be stored in an airtight container. Canning jars with plastic lids work well and will not corrode. The original pool shock containers are not air tight and anything within a couple feet will corrode.