How to Defeat Calcium Scaling in Your Swimming Pool

August 22nd, 2017 by

Calcium scaling is an unsightly white to white-grey stain that forms on pool sides when a pool’s calcium levels and pH are imbalanced. Not to worry though, calcium scaling is an easy thing to prevent with regular water testing and balancing. In fact, how susceptible your pool is to calcium scaling is directly related to how porous your pool material is. For example, a concrete pool is the most porous, where as vinyl liner and fiberglass pools are the least.

Although it may be difficult to do, calcium scales can be removed — and preventative steps can be taken to keep them from reforming. If your pool has a buildup of calcium scaling, here’s how to identify what type of calcium you’re dealing with, treat it and stop it from forming again.

Two Types of Calcium Buildup

There are two types of calcium scales that form in pools: calcium carbonate and calcium silicate. Calcium carbonate is white and flaky, and it’s fairly easy to take off. Calcium silicate, in contrast, is white-grey and more difficult to move.

Additionally, because calcium silicate takes longer to form, pools that have calcium silicate buildup on their walls often also have scaling in their pipes. If your pool’s scaling proves to be calcium silicate, you may need to hire a professional to remove the deposits in your pool and its filtration system.

To see what type of calcium scaling has built up on your pool, place a few drops of muriatic acid on a deposit. Make sure you follow all safety precautions and wear safety goggles when working with acids. Calcium carbonate will react with the acid and foam; calcium silicate will not. If you have any questions, you should make sure to contact a pool professional.

Removing Calcium Carbonate Scaling

If your pool has calcium carbonate deposits, you can remove them with a pumice stone, stain eraser or scale remover.

A pumice stone should only be used on hard surfaces, such as tile and concrete. Simply use the stone to scrub the deposits. To prevent scratching, be sure to keep both the stone and the surface you’re scrubbing wet.

Many commercially available stain erasers will also remove calcium carbonate. These products are designed to be applied in a specific area, so they often attach to a vac pole for easy application. If you decide to use a stain eraser, follow the manufacturer’s instructions.

Pool suppliers also carry calcium scaling treatments that are safe for all pool surfaces, including fiberglass, vinyl liner pools and concrete pools. These treatments are added to the pool’s water and dissolve the deposits over a period of several weeks.

Removing Calcium Silicate Scaling

The only reliable way to remove calcium silicate deposits is with a pumice stone — and a lot of hard work. These stains are notoriously difficult to scrub free.

If you have a vinyl or fiberglass pool, you won’t be able to use a pumice stone. It would scratch the pool. A calcium-scaling specific additive may remove the deposits, but these products can take months to dissolve calcium silicate. If you can’t use a pumice stone, you ought to contact a pool service provider in your area to use professional products that can quickly remove the deposits.

Preventing Future Calcium Scaling

As mentioned, calcium scaling is caused by an imbalance between the calcium levels and pH of your pool. Therefore, you can prevent future calcium buildup by addressing these two factors. You might want to do the following:

  • Lower the pH level of your pool’s water, because pH can have a larger effect on calcium scaling than calcium levels do.
  • Install an automatic pool cover that will reduce evaporation, because water that evaporates can leave behind calcium.
  • Remove calcium through a reverse osmosis water treatment.

Don’t let calcium scaling detract from your pool’s beauty. If your pool has calcium deposits, identify what type of calcium they are by using a muriatic acid test and then remove them — even if doing so requires calling a pool service provider. Once they’re gone, take precautions to prevent them from returning, like lowering your pool’s pH and installing an automatic cover.

Calcium scaling is an easy thing to prevent if you test your water regularly and perform routine pool maintenance.

Meet Our Expert

Written by

E.R. is Latham's Digital Marketing Manager. A life-long competitive swimmer, being part of the Latham team brings together a passion for pools and love of marketing - a real dream come true.

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