Pool surface looking a bit stained? It happens to the best of us. Over time, dirt and debris can settle and stain plaster and PebbleTec. Maybe your pop-up heads have moved dirt in such a consistent pattern for so long that there are permanent stains, or an algae bloom left permanent streaks. An acid wash is like exfoliation for your pool surface. The acid etches away a very small amount of the pool surface, taking with it stains, streaks, and other residue you don’t want. Because of its abrasive nature, acid washes are not an every year or even every other year occasion. But done properly, acid washes can remove stains and brighten surfaces.
We offer acid washes starting at $600 (depending on the size and condition of your pool). Weekly Service Members save $150 off their price!
In-ground pools have a foundation whose surface is either plaster, PebbleTec, or fiberglass. Plaster and PebbleTec are by far the most common in Arizona. If your pool has a smooth surface, you have plaster. If your pool looks like it’s coated in lots of small pebbles and beads, you have PebbleTec. Like any surface, plaster and PebbleTec can, over time, accumulate stains. Sometimes this may be due to neglect - for example, severe chemical imbalances, algae blooms, or rust stains from furniture or other metals left in the pool - but regardless of how careful you are, a pool surface will accumulate stains over time. These stains are hard to remove - a pole brush will generally not do the trick. Instead, a more intensive solution is required.
Have you ever cleaned tile grout with vinegar? The principle is the same with an acid wash for a pool. Vinegar is mildly acidic but acts on grout similarly to how muriatic acid acts on plaster or PebbleTec. The acid reacts with the surface of the pool, removing a very small layer of material, and along with it, any stains and streaks. This exposes a fresh layer of pool surface, which will be stain-free and brighter.
During an acid wash, the pool is drained so that the surface can be directly treated. Then, a diluted mixture of muriatic acid and water is mixed and poured across the pool surface. A scrub brush is used to spread the acid mixture evenly across the surface, and then the solution is immediately rinsed away with a hose. The pool is then refilled and balanced.
The short answer is that you should get an acid wash infrequently, generally no more than every 5 or more years. And because an acid wash requires draining the pool, in Phoenix, acid washes should not be performed during summer, so as to avoid heat damage to the dry pool surface. The long answer is:
Have you ever sanded veneered wood? You have to be careful of sanding through the layer of veneer. The same applies to a pool. The plaster / PebbleTec surface is a coating on top of the pool foundation, so you cannot remove too much of it, or you will expose the underlying foundation of the pool (for example, you could expose rebar). While pool surfaces are durable enough to endure acid washes every so often, you should not think of this as a yearly, or even every other year, activity. When your pool has clear, very visible staining, an acid wash is appropriate. There’s no hard rule, but we’d recommend avoiding acid washing more often than every 5+ years.
Acid washing requires draining a pool. Because of that, it’s important that temperatures are not too hot (generally, we’d say temperatures should not exceed 85-90 degrees). That means you should avoid acid washing during the Summer. Spring (February through early May) is ideal, as this will mean you have a fresh pool surface for the Summer swim season. Because the pool is drained and refilled, this also means you have fresh water for the summer, which can help reduce your chemical costs and help keep your pool clear and algae-free.
You may have heard of a chlorine wash. Functionally, the process of a chlorine wash is the same as an acid wash. A concentrated chlorine mixture is poured and scrubbed across the pool surface, and then rinsed away. Here are the scenarios where your pool may need a chlorine wash only, or a chlorine wash in conjunction with an acid wash:
A chlorine wash is often sufficient for pools that have a severe algae problem where the algae is deeply rooted into the pool’s surface, but otherwise the surface is generally in good condition. For example, if you have a dark green pool, with streaks of green on the surface that are not easily removed by brushing, then you may need a chlorine wash.
Fun fact: In cold climates, pool re-opening after Winter may sometimes involve a chlorine wash, but that’s not relevant for Arizona pools given pools are never drained and winterized here.
A chlorine wash before an acid wash may be required if your pool has substantial staining, as well as persistent and severe algae issues. While the acid wash will kill algae, we’d always like to use as little acid as possible given its abrasive nature. A chlorine wash prior to an acid wash can often remove algae stains from live algae blooms, meaning potentially less acid (or a more dilute acid solution) is required during the acid wash.
Yes! All equipment and materials can be purchased at a home improvement store and a pool supply store. It is a labor-intensive process, where timing matters (the acid needs to be promptly brushed and then rinsed after application), so it’s typically a 2- or even 3-person job. And most importantly, the chemicals are extremely caustic and dangerous, so proper protective equipment and proper procedure is very important. You can read our Acid Wash Guide here.
