Calcium chloride is the answer.

Yes, that’s the standard fix. You dissolve calcium chloride (pool-grade, not road salt) in a bucket of water and pour it around the pool edges while the pump runs. Follow the dosage on the bag based on your pool size and current hardness level.

Don’t use calcium hypochlorite (shock) unless you also need to raise chlorine. And don’t just dump it in one spot — it can cloud the water or stain the surface if it sits. Spread it evenly.

Test your water first. Most pools want 200–400 ppm calcium hardness. If you’re below 150, yes, you need it. If you’re just slightly low, don’t bother — it’s not a crisis unless your liner is old or you have a plaster pool that can etch.

A $10 calcium hardness test kit is cheaper than guessing. And if you’re using softened fill water, you’ll always be adding calcium. That’s normal.