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How to remove calcium in swimming pools

Calcium in swimming pools is the most complex and difficult of all the issues we treat.  This is because calcium can form in a pool for a variety of reasons.  White calcium (or scale) can form because pool owners often have difficulty keeping their pH in balance – particularly when their pool is new. High pH is a major reason for calcium formation and growth.

Calcium spots can also form due to poor interior application when the pool surface is being applied in a new or renovated pool. Poor application can leave air bubbles or voids in the concrete finish. These voids soon fill with water which then calcifies. Then, as the calcium in the void continues to expand over time it pushes calcium out through the interior and into the pool. This is referred to as a calcium nodule.

Calcium rich pool interiors

Calcium scale is another common issue in concrete pools as many coloured pool surfaces now use white cement instead of grey. White cement contains around 36% calcium hydroxide which contributes to the challenge of managing calcium. Once a thin layer of calcium has formed, it continues to grow because it attracts more calcium to it over time. Eventually the calcium will become bigger and sometimes harder than the concrete pool surface!

If you have calcium spots or scale we strongly recommend you do something about it soon. Calcium that is left untreated can lift, crack and break up your cement pool surface over time causing serious and costly damage to your pool. Sadly we often inspect pool surfaces that are almost completely destroyed by several hundred large calcium spots that have been left to grow. Our treatments can help prevent this from happening to your pool.

If you have a fibreglass pool with calcium buildup, we have a page dedicated to removing calcium from fibreglass pool surfaces here.

Typical signs of calcium scale and spots

  • White stain/lump that won’t brush off
  • White hard film on the pool surface
  • Hard white lumps that are growing
  • White ‘icicles’ running down pool walls
Calcium Stains in quartzon Swimming Pool
Calcium spots on dark concrete pool interior.

Remove calcium in swimming pools without draining

You do not have to drain your pool to remove calcium deposits. Our treatments almost always remove calcium deposits completely without draining the pool or acid washing the surface. Our proven treatment process is very effective in removing and preventing calcium deposits from Pebblecrete, Quartzon, vinyl lined and fibreglass pools. We also include long lasting prevention products to help it stay away once it is removed.

We do not recommend acid washing to remove calcium. Although this process often removes it initially, the challenge is that the calcium build-up will very often return within a few months if the water is not treated with calcium preventative. The good news is that our treatment is a fraction of the cost of an acid wash and more effective. This is because we add the needed preventives to the pool as part of the treatment. For more about acid washing click here.

If you are unsure of the type or cause of your calcium issue please feel free to contact us first.  There is more technical information about calcium below.

Calcium Stains in quartzon Swimming Pool
Calcium Stains in Swimming Pools The Pool Stain Removers 2
white calcium film on fibreglass
Calcium nodule

OPTION 1 – Calcium Stain Removal DIY kit

What We Do 1


Calcium Stains in Swimming Pools The Pool Stain Removers 3


Calcium Stains in Swimming Pools The Pool Stain Removers 5



  • 1 Litre of our powerful calcium release and prevention formula
  • 4 Kgs of our granular calcium dissolving compounds custom made for your stain
  • Phone support from our technicians
  • Simple step-by-step instructions included
  • Pool does NOT need to be drained
  • Kit is sent and electronically tracked by Fastway Couriers
  • Kids are back in the pool in just 7 days
  • Kit is $295 for pools 45,000+ Litres


Enquire now!

OPTION 2 – Calcium Removal – On Site Technician


Calcium Stains in Swimming Pools The Pool Stain Removers 3


Calcium Stains in Swimming Pools The Pool Stain Removers 5



  • 1 Litre of our powerful calcium release and prevention formula
  • 4 Kgs of our granular calcium dissolving compounds custom made for your stain
  • Complete 7 point on site water testing
  • Your pool does NOT need to be drained
  • Kids are back in the pool in 7 days
  • Visit is $405 for pools 45,000+ Litres


Enquire now!

Calcium deposits in pool

The reason calcium lumps and spots form can vary depending on many factors.  However, calcium deposits normally look like white spots or lumps on pool surfaces.

Hard white calcium balls or spots

Calcium spots are approximately the size of small round bean bag filling (approx. 2 – 6 mm in diameter) that appear randomly over the walls and floor of your pool and are difficult to brush away. These are also referred to as calcium nodules. Remember, this often occurs when a void of calcium rich water under the pool surface pushes calcium into the pool. In other words, these nodules form because of poor surface installation techniques. See diagrams.

White calcium icicles (nodules)

Most commonly, there are approx. 2–3mm wide and 3–12mm long and can appear to be ‘growing’ out of or ‘dribbling’ down the walls or floor of your pool. This type of hard white formation may indicate that a section of the pool surface has de-laminated (pushed out) from the main pool structure. Remember, if the calcium spot reappears in the same place after cleaning, delamination is likely to be the cause. Please call us if you suspect you have calcium nodules, surface cracking or white calcium spots in your pool. Finally, his type of build-up is often more noticeable in darker pool interiors.

Dirt trapped under calcium

Calcium can also form a thin calcium film that covers dirt or metal stains on the pool interior. Although calcium hydroxide is white, in this case, it may look brown or grey because the dirt has discoloured the calcium.  When this happens the calcium stain will look brown. Therefore, this type of staining cannot be removed with treatments such as chlorine or firm brushing because the calcium film over the dirt ‘shields’ the staining from brushing and chlorine.

White blotches from calcium

Calcium can appear in the form of blotchy areas can look like swirl marks on the bottom of your pool. When calcium forms on a pool surface it may leave a white film on the pool.  This film will visually highlight the imperfections in the surface. For example, our clients will often say that their pool looked great when it was first filled, but later on they can now see swirl marks, ridges or trowel marks that have appeared a short time later.

For more in depth scientific information about calcium in swimming pools click here.

calcium nodules swimming pool
Calcium has formed within a void in the pool render and has hardened once it has entered the main pool water.
calcium nodules in swimming pool
Calcium forming from small cracks and imperfections in the pool surface.