Do I need to run my pool pump 24/7 during a heatwave?

No. Heatwaves spike evaporation and algae growth, but running the pump nonstop is overkill. Most pools only need 8–12 hours of runtime; during a heatwave, bump it to 12–14 hours during cooler night or early morning hours. 24/7 wastes electricity and wears out your pump faster—check your skimmer and clean the filter instead.