Algae makes pool water slimy. Shock and balance.

Yes, it’s almost always algae. That slimy feeling on the walls and floor means organic gunk is building up — usually from low chlorine, high pH, or poor circulation.

The fix is straightforward: test your water, shock it hard (follow the label for your pool size), brush every surface, and run the filter 24 hours. Also check your pH and alkalinity — if they’re off, the chlorine won’t work right. Phosphates from lawn runoff or debris can feed algae too, so consider a phosphate remover if this keeps happening.

You’ll know you’ve got it when the water stops feeling slick and starts looking clear again. If it comes back, you probably have a circulation problem or a hidden source of nutrients.