Shock it hard.

Do a super-chlorination shock. Cloudy water is usually algae or bacteria starting to bloom, and the fastest way to kill it is to raise your chlorine level way above normal—like 10–30 ppm depending on your pool size and shock product.

Run your pump and filter 24/7 while you do it. The shock kills the organisms, then the filter catches the dead stuff. If the water is still hazy after a day, throw in a pool clarifier to help the filter grab the fine particles.

If it’s really bad (like you can’t see the bottom), skip the clarifier and go straight to a flocculant. That’ll sink the junk to the floor so you can vacuum it out. But floc requires manual vacuuming and you usually have to turn off the filter for a day—so it’s faster to clear, but more work.

Check your pH and alkalinity first. If those are off, the shock won’t work well.

Your pool will clear up in a day or two if you hit it hard.