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How to Remove Calcium Scaling from a Swimming Pool

Keeping a swimming pool clean takes a lot of effort. But as a responsible pool owner, you take all the right steps. You balance your pool water, you brush, and you vacuum. For the most part, your pool stays clean. But you start to notice an unpleasant white scale on the side of your pool. Maybe you’re noticing little white bumps forming on the walls, railings, and ladders. Or perhaps you’ve started to get the dreaded pool toe. The culprit is calcium scaling. Calcium is building up on the walls and other surfaces of your pool, and it’s not going away. If you’ve found yourself in a battle with calcium scaling, you know that it’s not easy to beat. But it can be done. So here is our guide to removing calcium scaling from your swimming pool.

How to Remove Calcium Scaling from a Swimming Pool [infographic]

Types of Calcium Scaling in a Swimming Pool

There are two types of calcium scaling, and one is much harder to beat than the other. Your typical, run of the mill scaling is calcium carbonate. Calcium carbonate can be a pain, but you can defeat it. The other type of calcium scaling is calcium silicate. Calcium silicate forms much more slowly, but once it’s there, it’s nearly impossible to remove yourself. Even worse, if you have calcium silicate, there is a very good chance that you also have buildup in your pipes. A calcium silicate buildup requires professional intervention.

You can tell the difference between a calcium carbonate and calcium silicate buildup by putting a drop of muriatic acid on the calcium scaling. If the calcium scaling starts to react with the acid and foam, you have calcium carbonate. If nothing happens, you’ve got calcium silicate. If that’s the case, contact The Pool Butler for a full professional cleaning. It’s important not to let a calcium silicate build up for too long, as it will eventually damage your pipes and your filter.

What Causes Calcium Scaling

Since there’s not much to do about calcium silicate, we’ll focus on calcium carbonate. Calcium scaling from calcium carbonate is the result of several factors all working in combination.

First, you need to have high calcium levels in the water, typically above 400 ppm. This can simply be the result of hard water. If you live in an area with hard water, you probably know it. You may have noticed calcium deposits on drains in sinks, showers, and tubs. Many homeowners in areas with hard water have water softeners in their homes. But the water that fills your pool usually doesn’t come from your home taps. If you don’t typically have hard water in your area, high calcium levels could be due to using calcium hypochlorite shock. Calcium hypochlorite shock adds calcium to the water and can result in unhealthy calcium levels. However, high calcium levels alone won’t cause calcium scaling.

The second factor in calcium scaling is water chemistry. High alkalinity and high pH create the perfect environment for calcium scaling. However, there is one last factor that really seals the deal: high water temperatures. High alkalinity, pH, and water temperature combined with hard water are a recipe for calcium scaling.

Removing Calcium Scaling

If you have calcium scaling, you have a few options for getting rid of it. First, you have the low-impact approaches. If those fail, there is a more extreme approach, but we’ll save that for later.

The easiest thing you can do to deal with minor scaling is to add some stain remover to your pool water. Most pool stores carry stain remover. Just make sure you get a remover that is safe for your pool material, as some stain removers can damage sensitive materials like vinyl.

If you only have calcium scaling in a small area, a little elbow grease goes a long way. The idea is to use a little acid to loosen things up and just scrub away the scaling. There are a bunch of ways to do this. Some people use toothpaste, borax, or baking soda. Our suggestion is to start with some vinegar, a mild acid, and pour or spray it onto the scaling. Then use a toothbrush, pumice stone, or some fine wet/dry sandpaper to remove the calcium scaling. It’s a bit of work, but it’s the simplest way to go for a small area.

Of course, this only works on hard surfaces. Never use anything abrasive on a vinyl pool liner. You don’t want to risk a tear. Luckily, vinyl tends to scale less easily than hard surfaces. So if you have a vinyl liner, you can probably get by with stain remover alone. If the stain remover doesn’t do it, use a nylon brush.

Using Muriatic Acid to Remove Calcium Scaling

If you have some tough scaling and the vinegar and pumice stone method isn’t working, there is another option. Consider this the nuclear option. Muriatic acid is a strong acid that can do some serious damage, so proper safety precautions are absolutely necessary. Here’s what to do.

First, collect your materials. You will need:

  • Muriatic acid
  • Plastic bucket
  • Plastic measuring cup
  • Plastic spoon
  • Plastic spray bottle
  • Scouring pad
  • Safety goggles
  • Rubber gloves
  • Respirator

The next step is to prepare your cleaning solution. First, put on your protective gear: goggles, respirator, and gloves. Then take everything outside. Never attempt to mix the cleaning solution indoors. Once you are suited up and have everything in a safe location, fill your bucket with a gallon of plain water. Carefully measure out 8 oz. of muriatic acid and slowly, carefully add the muriatic acid to the water. The order of ingredients is crucial. Putting in the water first and then adding the muriatic acid to the water minimizes splashing. The muriatic acid and water will react, generating heat. Add the muriatic acid slowly to avoid boiling and dangerous splashing. Once all of the muriatic acid is in the water, gently stir the mixture with your plastic spoon. Finally, carefully pour some of the mixture into your plastic spray bottle.

Once the mixture is prepared and ready in your spray bottle, spray some onto the calcium scaling. The solution will react with the calcium scaling and foam. Give the solution a minute to react, then scrub the area with your scouring pad. It is best to use a non-abrasive pad to avoid damaging the pool walls. Do all of this from outside the pool. Don’t reenter the pool until you have adjusted the pH back to a safe level.

Going the Professional Route

There are good reasons to allow professionals to do this work for you. If you are using the vinegar and scrub method, it can take a lot of physical labor. Depending on the area of the scaling, it could take hours of hard scrubbing. If you prefer not to spend the time and energy it takes, professionals can do it for you. The Pool Butler won’t use the vinegar and scrub method at all. We’ll use professional-grade solutions to quickly and easily remove the scaling.

If you think you need to employ muriatic acid, there is even more reason to go pro. Muriatic acid is extremely hazardous if mishandled. And in addition to the danger of the materials, your pool’s pH will drop dramatically. If you don’t want to mess around with a strong acid or be bothered with rebalancing the pool’s chemical levels, leave it to the pros. The Pool Butler has the tools and experience to do it quickly and correctly.

If your pool has moderate to severe calcium scaling, contact us to set up a free consultation. We’ll determine the best way to clean up your pool, and you will benefit from professional tools and know-how.

The Pool Butler