Preventive equipment service is not a spring-only ritual. In this valley the first failure is often a pump or heater on a 100-degree afternoon.
The pump
Listen. A squeal is a failing bearing or a dry lid O-ring sucking air. A hum with no water is a seized impeller or a closed valve. Capacitors fail in heat. We check amperage against the nameplate, not against memory. Replacing a capacitor on the pad is cheaper than replacing a motor after a weekend of no circulation and a green pool.
The heater and the salt cell
Scale in a heat exchanger and scale on a salt cell look related because they are: hard water plus high pH. We inspect both before the first cool evening and before the first heat wave. A cell that is not making chlorine is sometimes just a dirty plate, sometimes a failed power supply. Guessing from the store shelf wastes a Saturday.