An acid wash takes a thin layer off the surface of a plaster or similar finish. That layer takes most of the algae stains, mineral scale, and discoloration with it, and the result is a finish that looks much closer to new. For a lot of Florida pools, it's the most affordable way to get a clean-looking pool back.
It works best when the finish itself is still in good shape: smooth to the touch, no hollow spots, no flaking or bare patches. The problem is on the surface, so taking a little of the surface off solves it.
It won't help a finish that's already failing. If the surface is rough on your feet, chalky, peeling around the steps, or sounds hollow when tapped, washing it only removes more of a finish that's already thin. In that case, resurfacing is the real fix, and an acid wash would just delay it.
Because every acid wash removes some of the finish, it's not something to do every year. If stains keep coming back quickly, the cause is usually water chemistry or circulation, and fixing that matters as much as the wash itself. We'll check the surface before we quote, and tell you honestly which one your pool needs.