The general rule is to treat in this order:

  1. Sanitiser (chlorine or bromine)
  2. Alkalinity increaser (if needed)
  3. pH balancer (increase or decrease)
  4. Calcium hardness (if applicable)
  5. Shock treatment

This sequence helps prevent chemical interactions and keeps your water balanced more efficiently. Following a proper order is especially important during your initial spa start-up procedure.