Calcium buildup on fiberglass pool

Calcium on your Fiberglass pool?

In most cases, our calcium remover kit completely clears the hard white calcium buildup on fiberglass pool surfaces. It does this by dissolving the hard calcium and also comes with a prevention product to stop the calcium from coming back later on. The kit also restores the smooth blue finish of your fiberglass. However, if left untreated, this white build-up will spread across the pool surface and become thicker and more noticeable over time. For this reason, we suggest doing something about it as soon as possible.

Our fiberglass pool calcium remover compound dissolves hard calcium carbonate, calcium silicate, and phosphorus calcium scale from fiberglass pools without draining the pool or acid washing the surface.

Before After Calcium on Fibreglass The Pool Stain Removers 1Calcium on Fibreglass The Pool Stain Removers 2

These pictures show heavy calcium scale formation in need of our fiberglass calcium remover.

The fiberglass pool stain remover treatment without draining or acid washing. Our customer was thrilled with the result.

A thin layer of calcium scale has formed on the waterline of this renovated fiberglass pool.

Our fiberglass pool calcium remover fixed this issue without draining or acid washing. Our customer was thrilled with the result.

Before After
Before After MJ-Before-caclium-on-fiberglass-1152x1536MJ-after-calcium-on-fiberglass-1152x1536

Calcium scale formed on this new fiberglass pool after the water was not maintained during the startup.

Our calcium remover kit dissolved the calcium from the fiberglass pool surface and restored the original finish.

Our Company Credentials

SPASA members for complete peace of mind.
Certified technicians with 10 years experience.
Approved contractors for commercial and public pools.
We carry $2 million in insurance for your protection.

Causes of calcium buildup on fiberglass pool surfaces

Whitening or discoloration on fiberglass pool surfaces is normally a result of one of the following factors. We have ranked them in order from most common (1) to least common (5):

Calcium build-up on the pool surface

High pH levels in pool water may cause soluble calcium on fiberglass pools to precipitate onto the pool surface. When this happens, it often leaves a thin white gritty layer on the surface. As the picture shows, this white layer becomes very noticeable if the pool water drops below its normal level.

To help prevent calcium formation, test the pH and calcium hardness levels in your pool water.  Remember, High calcium (above 800ppm) often occurs for two reasons.  First, too much calcium chloride (calcium hardness) is present in the water. When this happens, it leads to calcium formation. Second, calcium-based granular chlorine will increase the calcium hardness levels in your pool. If your calcium levels are rising for no reason, then it is likely that granular chlorine calcium hypochlorite. is the cause.

Ask your pool manufacturer before adding calcium

Before adding any calcium chloride to your pool water, contact your pool manufacturer (not your pool store) and get the suggested calcium levels for your pool. Remember, each fiberglass pool manufacturer recommends different calcium levels.  Also, check that your pool store water tester knows that your pool surface is fiberglass and not plaster.  This is because plaster pools are much more common and use different water chemistry settings.

As the pictures show, our treatments remove calcium from fiberglass pools without draining the pool water or acid washing.

Salt Water pools in Winter

Remember, saltwater chlorine generators continue to add free chlorine to the pool when they are running So, if a pool cover is protecting the free chlorine from sunlight then the chlorine levels will continue to rise, especially when you cover the pool.  This means that the free chlorine levels can rise to dangerous levels quite quickly.  We have seen many cases where the free chlorine has exceeded 40ppm in these situations. Remember, if you are covering your pool, ensure that you reduce chlorine production.  You will not need to add much chlorine at all when the cover is on.

Calcium on Fibreglass The Pool Stain Removers 5

This partially drained fiberglass pool shows the white calcium formation. Notice how thick and widespread it has become along the walls. This client did not attempt any type of treatment hoping that it would just disappear over time.

Fiberglass pools typically pass through two phases as the surface begins to age. The gelcoat blue color will fade to white over time. This fading happens because of chlorine in the water, years of sunlight, and unbalanced water which all take their toll on the surface color. Remember, this color fading, which often starts after 15-20 years, is normal. This is not a sign of a faulty pool interior. Remember, if your pool is losing color after 20 or more years then ageing is the likely cause.

The second stage of ageing is when fiberglass pools (20-30 years old) start to develop a very fine white powder that appears when brushing the pool.  The powder is actually degrading gelcoat that has broken down over time.  This white powder will eventually disappear in sections of the pool revealing the lower dark brown layers of fiberglass. This breakdown is usually first noticed in high-friction areas such as steps and benches. Remember, the best way to extend the life of your fiberglass pool is to maintain the water.

calcium on fiberglass

This Fiberglass pool has a heavy layer of calcium formation on the surface. You can clearly see that the areas where the calcium has flaked away that the gelcoat color is in tact and not bleached. 

Bleaching in a fiberglass pool usually happens when the pH and the chlorine levels are both very high at the same time. Remember, if the pool water remains unbalanced, with very high chlorine, it may start bleaching the surface.  Although fiberglass pools can resist bleaching from water imbalance, they cannot withstand this for very long.  So a long period of unbalanced water may result in fading or bleaching of the surface. Remember, when winterizing your pool, make sure that your pool guy does not over-chlorinate the pool just before closing.  If they do this, then it could damage the surface over the winter due to prolonged high chlorine levels in the pool water.

Gelcoat bleaching from unbalanced water is often smooth and is non-responsive to cleaners and acids. In some cases, rubbing the surface with fine sandpaper can appear to remove this discoloration.  However, doing this incorrectly will only remove the bleached gelcoat layer in your pool. Remember, rough sanding the gelcoat will leave your pool susceptible to future staining and reduce the life of your pool.  Only rub the pool surface with approved products.

WARNING: Careful with pool covers

Some pool owners feel that testing the water during winter (or when a pool is covered) is not needed. Often, these same pool owners are horrified when they remove their pool cover and discover extensive surface bleaching. Remember, it is a good idea to check your water during winter, even if you have your pool covered.

Our treatments can sometimes help reduce the visual impact of surface bleaching.  However, there are cases where nothing can remove fiberglass pool surface bleaching. This is because chlorine has oxidized (or faded) the pigment (color) within the gelcoat resin.

Aside from bleaching, sometimes calcium buildup on fiberglass pool surfaces can happen if the water is out of balance during winter. Our calcium treatment kit will remove this calcium buildup on the surface.

Please contact us for further information if you feel your pool may have this issue.

Gelcoat bleaching Fibreglass

Possible Gelcoat reaction with the pool water. Notice the smoothness of the white film and the distinct separation between the vivid blue and white along the waterline. Our treatments are sometimes effective with this issue.

The layers of a fiberglass pool

The diagram below shows how the layers of material are bonded together. Notice that most of the thickness of a fiberglass pool comes from the structure and not the blue decorative layer on the surface.

layers of gelcoat

This sectional diagram shows the layers of a fibreglass pool from top to bottom. Notice that the pool water can slowly circulate through the top surface layer of gelcoat. This process can allow the gelcoat to be effected by poor water chemistry.

gelcoat fading in fibreglass

In this image the light blur gelcoat is breaking down revealing the brown fiberglass structure under it. This pool is 32 years old.

If you sprinkle an undissolved sodium bicarbonate or baking soda directly into the pool, it can form a stubborn white film to appear on the pool surface. To avoid this, ensure that you dissolve it first in a bucket of water before you add it to the pool. Remember, when an alkalinity increaser is first added to water, it will be milky white, and then as it dissolves, the water will become completely clear. So, dissolve it in a bucket first, and then when the water is clear, then add it to the pool. Remember, it is best practice to balance the pH before adding sodium bicarbonate.

In very rare cases, the gel coat can discolor and remain white if it has not been cured properly during manufacturing. If your pool has this issue, it will become obvious within the first few hours after the pool is filled with water. This discoloration occurs because the uncured resin on the surface is very porous. This allows the water to penetrate into the surface resin and bleach the pool surface. Remember, this bleaching is permanent and cannot be fixed. Consequently, complete resurfacing of the fiberglass is required. So if your pool remained the same blue for the first day of its life then it is not a manufacturing issue. Keep in mind that this issue is very unlikely. Usually, a calcium buildup on fiberglass pool surface is the reason for the white appearance.

Don’t Drain or Acid Wash a Fiberglass Pool

DO NOT drain or acid wash to remove a calcium buildup on a fiberglass pool – ever! This is because very often any calcium buildup on the fiberglass pool surface is not removed using this method, if you insist on draining, we suggest using a licensed and insured professional. Remember, to do this properly, your pool walls must be properly cross-braced and secured to prevent buckling, cracking, or warping when you release the water. Finally, when the pool is empty, hydrostatic ground pressure can force the pool upward, out of the ground. If this happens, you’ll need the contractor’s insurance to pay for a new pool. Remember, you cannot push the pool back down if an uplift occurs.

Pool walls buckle inward from ground pressure. Photo credit: APCO Pool Specialties

Pool walls buckle inward from ground pressure. Photo credit: APCO Pool Specialties

Swimming pool pushed upward while empty. Photo Credit: Pool Water Recycling

Swimming pool pushed upward while empty. Photo Credit: Pool Water Recycling

Calcium Removal

Most Popular
Removal DIY Kit

Calcium Removal DIY kit

$ 0
(inc. Tax & Shipping)
Removal DIY Kit

Calcium Removal –
On Site Technician

$ 0

How fiberglass pools are made

This short video shows the process followed to make a new fiberglass pool shell. Notice how thin the topcoat is that is the first product sprayed onto the mold. The sprayed surface becomes the inside (or wet side) of your pool when completed. This is why it is so important to maintain your pool water chemistry. Remember, this exposed thin outer layer is delicate. Also, it’s exposed to water, heat, and elements all year round so take good care of your pool. Remember, you can damage this thin surface by not taking care of the water. Finally, the outer layers of rough fiberglass provide structural stability for the entire pool.