Pool Scale & Stain Reduction
/Metals and Calcium in the pool water are invisible to the naked eye, though in high enough quantities, they can form into visible (and unsightly) stains and scaling on the pool walls and floor.
Scale can appear in a variety of ways from rough, white deposits forming on the pool surface to salt crystallisation forming on the salt cell. The main causes of scale formation are high calcium levels and poor water balance.
Once staining has occurred, you will need to treat the stains of to remove them from the surface and depending on the type of stain, the treatments will differ.
Types of Pool Stains
Swimming pool stains can be categorised into two types: organic and inorganic stains.
Organic stains typically result from natural matter like leaves or algae sitting on the pool surface for an extended period of time. You can test if a stain is organic by pouring granular chlorine on it and waiting for a few minutes to see if it fades or disappears.
To remove organic stains, brush the affected area often and raise the Free Chlorine up to 5ppm. You can also use specific stain removers that contain citric acid.
Inorganic stains, on the other hand, are caused by metals like iron or copper in the water. Iron stains are more common in bore water than town water, but can be tested for in our shop.
To remove iron stains, you can use specific stain removers that contain ascorbic acid. Copper stains, on the other hand, can be caused by the use of copper-based algaecides or low-quality chemicals. You can remove copper stains by using a sock filled with dry acid and rubbing it on the stain.
After removing the stains, it is essential to keep the metals “in solution” and prevent them from sticking to the pool surface again. Sequestrants keep the metals “in solution” by attaching to metal particles in the water, preventing them from causing stains. Its important to not that sequestrants break down over time and require regular additions to remain effective.
Also, there is no practical way to remove iron or copper from the water without replacing the majority of the pool water with new water that does not contain these metals.
Copper stain on a marbelite surface
There are 4 ways metals and calcium can physically affect your pool.
Low Calcium levels in the water will generally try to pull calcium from the surface of your pool to ‘balance’ itself. This usually will accumulate onto the walls of your pool as calcium deposits and can be difficult to remove. - Having a balanced calcium level and a scale inhibitor in the water will stop the scale from coming out onto the surface.
If there is visible scale on the walls/floor of your pool already, a scale inhibitor will stop more scale from forming and reduce the scale back into solution (back into the pool water).
Calcium scale also forms on the salt cell. This reduces the effectiveness of the salt chlorinator to produce chlorine even if you have a ‘self-cleaning’ version. By reducing and softening the build-up on your cell, will keep your chlorine production up and increase the life of your cell too.
Concentrations of heavy metals such as iron and copper that drop out of solution (mixed with water) cause various coloured, unsightly staining on both the walls and floor of the pool or around the skimmer box, pool returns, and lights. By keeping these metals ‘in solution’ and not allowing them to ‘plate out’ onto the surface will keep your pool surface looking its best!
How we treat pool stains
We stock two different scale inhibitor products.
Aquaguard from LoChlor Products is a Cell Protector, Scale Inhibitor & Metal Remover.
We use 500ml to 50,000 litres of pool water every 3 months to soften any build-up that has formed. This is added to the pool with the pump and filter running so that it can make its way through the filtration system of the pool and distribute evenly to make sure that all surfaces of the pool and equipment are covered.
We also use Aquashield 3 made by Focus Products.
1 litre will treat a 50,000 litre pool for 3 months, and also comes in 250ml sachets for preventative regular monthly dosing.
This product also assists in removing existing scale from pool walls particularly ceramic aggregate finishes and it also creates superb clarity in the water by ensuring calcium remains in solution. This will also keep build up on salt chlorinators soft and easy to clean.
*Pools using bore or dam water should use a scale inhibitor regularly to ensure that metals remain in solution and don’t stain the surface.
Benefits of Scale and Stain treatments
Prevention of calcium and magnesium build up on pool surface.
Prevention of staining when metals drop ‘out of solution’.
Assists with softening calcium build up on the salt cell to ensure chlorine production is not inhibited.
Assists in the removal of metal stains.
If you notice any scale or staining forming on your pool surfaces, either of these products could work for you. By bringing in a sample of your pool water along with any photos on your phone for reference, our team can identify the best course of action to help you.
Alternately you can book one of our mobile service technicians below to come to you and assist with your stain and scale issues.
