An acid wash strips a very thin layer off the plaster to reveal clean material underneath. It's the right tool for widespread mineral scale, stubborn algae staining that brushing won't touch, and the dull, blotchy look plaster takes on after years of hard Valley water.
It's not the right tool for every stain. Isolated metal stains, like a rust spot from a bobby pin or a copper stain near a return, can often be lifted with targeted stain treatments without draining the pool at all. Since every acid wash thins the plaster, it pays to use it only when the whole surface needs it.
For most plaster pools, that means an acid wash every three to five years at most. If your plaster is already rough, thin, or showing gray patches underneath, an acid wash won't save it; that's a resurfacing conversation.
When we do an acid wash, the refill matters as much as the wash. Freshly exposed plaster is vulnerable, so the start-up chemistry has to be balanced carefully in the first days. We'll look at your surface and tell you honestly which option makes sense.