How to Remove Stain and Scale

For many pool owners, stain and scale become a problem at some point in their pool owning experience. Unsightly blemishes on your pool’s surface and damage your pool’s surface can be frustrating to say the least. Below we’ve included some background information and tips to remove and prevent stain and scale occurrences.


Scaling is caused when water evaporates, leaving calcium deposits behind just above the water line. There are two kinds of scaling that can occur in your swimming pool. Calcium Carbonate and Calcium Silicate. Calcium Carbonate is the better of the two as it’s much easier to remove than Calcium Silicate.

pool scale

Calcium Carbonate can be removed using a pumice stone or with a stain and rust remover, such as Super Clear. Super Clear will lift of the Calcium Carbonate and prevent it from occurring in the future. Easy Care Plus Descaler and Stain Remover is a high performance calcium descaler, iron stain, and scum remover that leaves your pool fresh and clear. Keeping your water healthy and balanced will also reduce scale build up. It’s best to treat the scale then keep a close eye on your water chemistry as unbalanced water will cause scaling to re-occur.

Calcium Silicate occurs when the scale has been present and untreated for a long period of time. The scaling will have a gray tint as opposed to Calcium Carbonate which will appear white and flaky. This type of scaling is more resistant to scale and stain removers and has to be removed with a pumice stone and some strong motivation to get the job done. This is why it’s important for homeowners to eliminate scale build-up in the Calcium Carbonate stage. If left un-managed for too long, scaling can damage pool equipment and require pool owners to acid wash their pool. A process that involves draining your pool then stripping the top layer with acid, giving your pool a brand new finish.


Staining is a bit different than scale and is caused by metals or organic pollutants such as algae or leaves. After entering into your pool, metals or organic pollutants settle and begin staining the walls and floor of your pool. They often appear after a new batch of chlorine or after the pH raises in the pool. Both stains can look similar to one another, but behave in different ways.

Organic stains are easier to get out and often time, just require pool owners to keep FC or free chlorine around shock levels. Metal stains can be a bit harder to remove from your pool due to their resilience to come back. They enter your pool by local water supply or by certain types of algaecides, many mineral systems, and ionizers. If you suspect your water supply to contain high levels of metals, you can get iron free water trucked in.

Another way metals can be introduced is from a copper heat exchange found in pool heaters. Once the pH level in your pool drops below 7.0 for a long period of time, copper can begin to leach in your pool. If you think you are developing stains due to metal, check it by doing a simple test. Simply hold a Vitamin C tablet up to the stain for 30 seconds or so. If they stain is removed or lightens considerably, you do in fact have metal staining.

If you do have metal stains in your pool, there are a couple of things you can do to eliminate it. You can use a stain an rust remover such as Super Clear to remove metal staining or drain and refill the water in your pool for a fresh start. If the staining is considerable you may want to acid wash the pool once drained.

Using a stain and rust remover will remove the stains and prevent other stains from developing, but it is not a perfect solution. Using a stain remover works by binding to metals in your pool and preventing them from forming into stains. Over time the binding agents will eventually will break down if more stain and rust mover is not applied. Unfortunately, the only way to completely remove metals from your pool, is to drain and refill using iron free water. Using stain and rust remover before draining your pool will ensure all metals are eliminated from your pool surface before you replace your water.

If you have a question or concern, leave a comment below for one of our trained experts or reach out to us at 800.772.0467.

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When Kevin’s not enjoying the water himself he’s engaging himself in the wide world of pool and spa knowledge which he passes on to our customers through producing content for our blogs and website. Outside of the pool world you can find him enjoying life with friends, family and his off the wall dog Brixton.