That pink pool water is bacteria, not algae. Shock it hard.

You’ve got a case of Serratia marcescens or similar bacteria. It thrives in warm, stagnant water with low chlorine. Pink slime is gross but fixable.

Rapid answer: super-chlorinate (shock) the pool to 10–15 ppm free chlorine, then brush every surface. Clean or replace your filter media. Kill that stuff.

The long version: pink is not algae. Algae is green or yellow. This is a biofilm bacteria. It loves low circulation, high pH, and poor sanitation. So after shocking, make sure your pump runs 24 hours. Test your pH (should be 7.2–7.4) and keep chlorine steady. If it comes back, check for a lingering biofilm in the filter or dead spots in the pool.

Don’t panic. It won’t hurt you, but it looks awful. Fix the chemistry and circulation, and it’s gone in a day or two.