How often should you really shock your pool?

Chlorine demand, not the calendar

Shocking is a response to combined chlorine, not a fixed weekly ritual. If your free chlorine and total chlorine readings are within 0.2 mg/l of each other, the pool is keeping up on its own and a shock dose will only cost you money.

The three numbers that matter

Test free chlorine, total chlorine and pH before you decide. A gap of more than 0.5 mg/l between free and total chlorine means chloramines have built up and a shock dose is genuinely due. Above pH 7.8 the chlorine you already have is doing far less work than you think.

When to shock regardless

After heavy rain, after a party, after any visible algae bloom, and at the start and end of the season. In a Cyprus summer with heavy use, most domestic pools land on roughly every three weeks rather than every week.