How to Fix Pool Plaster Etching

Written by Michael Dean
July 5, 2023

fixing swimming pool plaster etching

Pool plaster is one of the most common finishes of a concrete pool. While this material is durable, easy to work with, and relatively inexpensive, as with most things, plaster comes with its own range of issues over time. One such issue you may come across is etching. In this article, we will explore why etching happens in pools, how to fix it, and what steps you can take so that it doesn’t happen again!

Main Takeaways

  • Etching is caused by an improper balance of chemicals in the water, such as chlorine, calcium, or low pH. The chemical imbalance will dull and eventually corrode the surface.
  • Etching is not only unsightly and uncomfortable but also a breeding ground for algae.
  • You can fix pool plaster etching by sanding it down, chipping and replastering, and resurfacing the entire pool.
  • The best way to prevent etching is to maintain proper water chemistry.

What Is Etching?

The term “etching” refers to the plaster surface of your pool being dulled or corroded by chemicals in the water, such as chlorine, calcium, low pH, and low alkalinity. You may have etching on your pool plaster if there are surface irregularities, such as dents in the plaster or rough surface areas. Although etching itself does not discolor the plaster, it will discolor the plaster over time as etched areas become stained much more easily.

pool plaster etching

What Causes Pool Plaster Etching?

Over time, low pH levels in your pool can eat away at the plaster, causing dents and lines to develop. Essentially, etching is caused by your water being too acidic. If your pool’s pH or alkalinity levels are too low, the water can become acidic and slowly erode your plaster.

Difference Between Etching And Scaling

Scaling occurs when your pool water’s pH level is too high, and calcium carbonate solidifies on the pool plaster. Scaling may look like algae or debris on the surfaces of your pool, but the scales are much more difficult to remove.

Etching occurs when the pH level is too low in your pool, and scaling occurs when the pH level is too high in your pool.

What’s Wrong With Etching?

Etching in and of itself may not be dangerous or harmful, but it can be a breeding ground for many things that could harm your pool and the swimmers.

First, at the surface level, etching is unsightly. Although etching itself does not have a color (unlike scaling), etched areas become very easily stained. As those areas stain, the dents in the plaster will become more visible, and your pool plaster will lose its luster.

Further, these dents and lines are a safe place for dirt and algae to grow and fester. Etched areas are a lot more difficult to clean efficiently and effectively, making them breeding areas for unwanted debris and bacteria. The last thing you want is for your pool plaster’s lifespan to shorten drastically because of algae you cannot properly clean out.

Finally, etched areas are simply rough and can be uncomfortable for swimmers who accidentally brush their bodies against these areas. This can irritate the skin and ruin the entire swimming experience.

How To Fix Pool Plaster Etching

Now that you’ve identified that you have etched areas in your pool plaster, how do you fix this problem? Unfortunately, etching is permanent. You can’t undent a dent after all! But you can do a few things to help remedy this issue.

Sand It Down

If your pool plaster etching problem is confined to one area and is only at the very beginning of the issue, one thing you could do is sand it down to reveal smooth plaster underneath. 

Nowadays, you can wet and dry sand pool plaster, meaning you can get away with sanding the surface without needing to drain the water first. But whether you wet or dry sand the pool plaster will depend on the type of sandpaper and sanding block you use, so check the manufacturer’s instructions first.

Chip It Out and Replaster

If the etching is quite bad in one area of your pool, one option you have is to chip out the section of plaster and replaster the section. Repairing pool plaster can be costly both in terms of time and money. This is not an easy DIY remedy, so consider hiring a professional to do the job for you. But if you’d rather do it yourself, check out my article on how to repair pool plaster.

Replaster The Whole Pool

Finally, if the etching has gotten quite bad in your pool – so bad that the entire surface of the pool feels rough – the only solution is to replaster the whole pool.


This is the best method to fix pool plaster etching. At the end of the day, you can’t really “fix” pool plaster etching as it is permanent damage. So, the best thing you can do as a pool owner is to prevent pool plaster from etching in the first place.

Let’s dig a little bit deeper into this!

How To Avoid Pool Plaster Etching

Here are my top tips to avoid pool plaster etching. 

Maintain Your Pool Water Chemistry

The most important thing to avoid pool plaster etching is to keep your pH level and calcium hardness balanced. The main cause of pool plaster etching is improperly balanced chemistry, so if you test your pool water frequently and top up on the necessary chemicals, you should be able to avoid etching.

Brush And Clean Your Pool Frequently

Alongside maintaining your pool water chemistry, you should also clean your pool frequently. Brushing the walls will prevent low alkaline water from forming lines in the plaster, and cleaning the pool regularly is a good practice that will make the swimming pool look great and maintain the chemistry levels.

Pre-Dilute Acid Before You Add It To The Water

When adding muriatic or cyanuric acid to your pool water, never pour the acid directly into the pool. First, dilute the acid in a bucket so that the acid can mix with the pool water more easily. Ensure that you pour the acid into the water and not the other way around to avoid chemical boiling.

Don’t Add Salt Within 30 Days Of Replastering Your Pool

Avoid using a salt chlorine generator in your pool or adding salt within the first 30 days after plastering. Salt is very abrasive, and saltwater is up to 5 times as abrasive as freshwater. Your new plaster is much weaker and can begin etching or damage if you add salt too early.

Bottom Line

Pool etching is a common problem caused primarily by improperly balanced chemicals in the water. Every pool owner knows the importance of maintaining proper water chemistry, but now you know that not looking after your pool water can also lead to permanent damage to your pool plaster. The last thing you want is to have to replaster your entire pool prematurely!

Head to my other articles below to learn more about other common pool plaster issues.

More questions about pool plastering? Feel free to reach out; I’m happy to answer.

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