Double or triple your normal shock dose after a party.

Yes, you need to shock it harder than usual. After a bunch of swimmers, your pool is full of sweat, sunscreen, pee, and whatnot. That stuff eats up chlorine and creates chloramines (the stuff that stings eyes and smells like a YMCA locker room).

The proper way: raise free chlorine to 10–30 ppm, depending on your stabilizer (cyanuric acid). Test your pH first and get it between 7.2 and 7.4 — that makes the shock work better. Use a non-stabilized shock like calcium hypochlorite or Lithium hypochlorite so you don’t drive CYA through the roof.

Add the shock in the evening (sunlight burns off chlorine), run the pump overnight, and keep it running until the chlorine level drops back to normal. Don’t let anyone swim until free chlorine is below 5 ppm (or your local health code limit).

Your pool will thank you, and so will tomorrow’s swimmers.