# Calcium scaling: repair options for tile and plaster

> Scale is removed with a chemical treatment at $40 to $150, a professional descale at $300 to $700, or a drain and blast at $600 to $1,200. What works where.

Canonical: https://poolresurfacingguide.com/calcium-scaling-repair/

Last updated: 2026-11-09

Calcium scale is a deposit, not damage, and it comes off in one of three ways depending on where it is and how thick it has become. A chemical remover costs **$40 to $150**, a professional descale **$300 to $700**, and a drain and media blast **$600 to $1,200**. An acid wash at **$400 to $800** works once on sound plaster and backfires on etched plaster.

## What scale is

Scale is calcium carbonate that has come out of solution and bonded to the surface. Water holds calcium in solution up to a point; when pH, calcium hardness, or alkalinity rise past that point, the excess deposits on the nearest surface.

It appears first where water evaporates, which is the waterline and the tile, and later on the plaster and inside the heater. It feels rough, looks white or grey, and does not brush off.

## The repair options by location

| Location | Method | Cost |
|---|---|---|
| Waterline tile, light | Pumice block and remover | $40 - $120 |
| Waterline tile, heavy | Professional descale | $300 - $700 |
| Plaster, light film | Chemical descale, circulating | $150 - $400 |
| Plaster, heavy | Drain and media blast | $600 - $1,200 |
| Fittings and ladders | Remover and hand scrub | $40 - $150 |
| Heater element | Descale or replace | $150 - $600 |

The distinction that matters is sound plaster versus etched plaster. Scale on a sound surface can be removed. Scale on a surface that has also been etched is a symptom of a pool that has been out of balance in both directions, and removing it leaves a rough floor.

## Chemical descaling

A scale remover is an acid-based product, applied to the surface or circulated in the water at a controlled dose. It works by dissolving the calcium carbonate faster than it attacks the plaster, which is a matter of concentration and contact time.

It is effective on light film and on tile. It is slow on thick scale, and it is not a substitute for mechanical removal when the deposit is millimetres thick.

Follow the label dilution and do not increase it. A stronger mix does not remove scale faster in any useful way; it removes plaster faster, which is the failure mode.

## Drain and media blast

Heavy scale on plaster is removed by draining the pool and blasting the surface with a fine media, usually glass bead or a similar abrasive, at low pressure. The media breaks the deposit off without cutting into the plaster underneath.

At $600 to $1,200 it is the most effective method for a scaled pool, and it is also the point where the surface condition is revealed. A pool that has been scaled for years often has etching underneath, and the blast shows it.

That is why the quote should include an assessment after the blast. If the plaster is rough and chalky once the scale is gone, the next step is a resurface at $4,000 to $10,000, not another descale.

## Grout after a descale

Scale bonds to grout as well as to tile, and when it comes off it takes the top layer of grout with it. A waterline that was scaled for years often shows open, sandy joints once the deposit is gone. That is a regrouting job rather than a cleaning job, and it is worth pricing at the same time: leaving open grout exposed lets water into the tile bed, which is how a cosmetic descale becomes a tile replacement at $1,500 to $5,000. Inspect the joints after the wash and before the pool refills, because that is the cheapest moment to fix them.

## The acid wash question

An acid wash is a whole-pool acid application that removes a thin layer of plaster along with the scale and stains. At $400 to $800 it is cheaper than a media blast and more aggressive than a chemical descale.

It works on sound plaster with light scale. It fails on etched plaster, because the etch is already a loss of cement, and the acid removes more. A pool that is chalky before the wash will be rougher after it.

Test before choosing: rub the plaster with a wet hand. Chalk on the palm means the surface is giving up material, and an acid wash is the wrong tool.

## Six steps, and what is excluded

1. Identify where the scale is: tile, plaster, fittings, or heater.
2. Test the plaster with a wet hand for chalk.
3. Try a chemical remover on a small area first.
4. For thick scale, book a drain and media blast.
5. Rebalance the water before refilling.
6. Fix the cause, or the scale returns.

Step six is the one that decides whether the repair lasts a season or a decade. Scale is a water-chemistry outcome, and the same water will produce the same deposit.

A descale does not include rebalancing, a partial drain and refill, or the tile grout that may need replacing after the scale is removed. Those are separate lines.

It also does not include the resurface that may be needed if the plaster is found to be etched. Ask for that possibility to be priced before the work starts, so the decision is made with numbers rather than after the fact.

## The short version

Light scale on tile is a $40 to $120 job. Scale on plaster is $300 to $1,200 depending on thickness and method. Acid washing is for sound plaster only. The prices by scenario are in [calcium scaling: what a fix costs](https://poolresurfacingguide.com/calcium-scaling-cost/), prevention is in [calcium scaling: how to prevent it](https://poolresurfacingguide.com/calcium-scaling-prevention/), and the symptoms are in [calcium scaling: warning signs](https://poolresurfacingguide.com/calcium-scaling-signs/).