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Maintaining a Concrete Pool

Concrete pools have plenty of advantages. They can be built to any size and shape and last for 50 years or more. But they also require special care. The nature of concrete means that it is susceptible to certain issues that are not present with vinyl or fiberglass pools. Because concrete is filled with microscopic pores, it can host bacteria and algae that eventually will affect the water quality in the pool. Strong chemicals can also affect the concrete or the plaster that is often put over it. Another common problem with concrete is cracking. All of these issues mean that you need to take special care when maintaining a concrete pool. But with the right care, a concrete pool can last for decades.

Maintaining a Concrete Pool [infographic]

How Concrete Pools Are Made

Concrete pools have one major advantage over vinyl and fiberglass pools. They can be made in any size or shape you like. That’s because unlike vinyl and fiberglass, the pool is not premade. Instead a hole is dug in the desired shape and depth of the pool. After the hole is prepared, the walls are fitted with rebar. The rebar will provide support for the concrete that will be poured. Once the rebar is in place, a mixture called gunite is sprayed onto the rebar to form the walls and floor of the pool. Gunite is a mixture of sand and cement. This mixture is a form of concrete.

Once the gunite has cured, the walls and floor of the pool will be covered or treated in some way. One common way to smooth over the gunite is to apply a layer of plaster. The plaster will form a smooth cover over the rough gunite, protecting swimmers from scrapes and other injuries. Another way to smooth over the concrete is with tile. This is a very traditional style and is found in many public pools. Sometimes the concrete is simply painted. In this case, the pool needs a thick paint that can smooth over the rough gunite surface.

Features of Concrete

Concrete as a material has some features that affect how you care for a concrete pool. One feature of concrete is that it is porous. This means that it is filled with tiny microscopic pores which can harbor bacteria. If the pool and its concrete walls are not cleaned regularly, these bacteria can flourish. Too much bacteria can affect the chemical balance and even visual quality of your pool water. The type of covering placed over the concrete can affect how significant of an issue this is. For example, a concrete pool that is completely tiled will have much less of an issue with bacteria than a pool that is plastered.

Another feature of concrete is its reactivity. Concrete doesn’t mix well with certain chemicals. For instance, if you’re pool is concrete, you can forget about creating a saltwater pool. The salt attacks the concrete and weakens it, greatly reducing the lifetime of your pool. Even regular pool chemicals, such as chlorine, will eventually eat away at the concrete. For this reason, concrete pools eventually need to be resurfaced.

With concrete pools it is also important to pay attention to the chemical balance in your pool water. If the pH is to low, acidic water can corrode and eat away at the concrete. This creates little pits and rough spots that can harbor bacteria and algae growth. Similarly, if the water has too little dissolved calcium, it will leach calcium out of the concrete walls. This weakens the walls and has a similar effect to corrosion, roughening the surface of the wall.

Special Care for Concrete Pools

If you have a concrete pool, you will have to take special care of it in ways you might not for a vinyl or fiberglass pool. Besides maintaining a constant balance of chemicals in your water, you will need to keep the concrete itself clean. The best way to do that is by simply brushing the walls. You can use a hard bristled brush attached to a telescopic pole to brush the walls and floor of your pool.

Brushing a pool is just like brushing your teeth. The goal is to remove bacteria or algae that have built up on the porous surface of the concrete, just like you would remove plaque from your teeth. After brushing, wait a few minutes to allow the loosened bacteria and algae to sink to the bottom of the pool. Then you can use a pool vacuum to clean along the bottom of the pool and collect the material you brushed off.

No matter how well you care for your concrete, you will eventually need to resurface the pool. To do this, you will need to drain the pool. Before draining the pool, make sure that you are aware of local regulations that may regulate pool water disposal. Because pool water has chemicals in it, it may not be advisable to pour it down storm drains. If the water is too acidic, you may not even want to pour it out on your lawn, since it could damage grass and plants. If your pool is large and your lawn is small, you also want to avoid flooding your lawn. Too much water could drown plants and create runoff full of dirt and mud.

Acid Washing a Concrete Pool

If a concrete pool is not adequately cleaned on a regular basis, it may be attacked by algae. If the pool has been attacked by algae or if inadequate cleaning has led to stains, it may be time to acid wash the pool. Acid washing uses a potent acid solution to burn off the outer layer of concrete or the plaster covering it. This reveals a completely fresh and clean layer beneath. If done properly, it can be a great refresh for your pool. But because this process involves harsh chemicals, it may be best to leave it to professionals. The experts at The Pool Butler are experienced in acid washing and can acid wash your pool safely.

Acid washing works by burning off a thin layer of the walls and floor of your pool. Because of this, it can only be done a limited number of times. It is best to reserve this rather extreme form of cleaning for serious damage and staining that cannot be removed otherwise.


Because concrete is rigid, it is susceptible to cracking. Cracking usually occurs when the soil around a pool shifts. This may be due to a change is the water table or settling of the soil. It can also be the result of seismic activity. It is important to treat cracks as soon as you find them. Small cracks can quickly become big problems if left untreated. When a crack is small, it can usually be sealed. If it grows, it can require a complete resurfacing or even larger repairs.

The Importance of Regular Care

The key to maintaining a concrete pool is making sure to care for it regularly. If you maintain a routine of cleaning, testing and adjusting the water balance, and inspecting your pool, you can avoid some of the bigger problems. Of course, this requires a significant amount of time and energy. If you want to enjoy your concrete pool but don’t have the time to care for it properly, you are in luck. The Pool Butler can provide the regular service your pool requires. We’ll maintain pH and chemical levels and clean the pool as necessary. Just contact us online to set up a consultation and we will find the level of care that is right for your pool and your budget.

The Pool Butler