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The Home Depot

3 Causes of High Alkalinity in Pools

Pro Referral > Home Guides > Pool and Hot Tub > 3 Causes of High Alkalinity in Pools
3 Causes of High Alkalinity in Pools

Having a swimming pool on your property is a big plus, especially during hot summers. A relaxing swim, having a pool party, and playing Marco Polo are just a few of the fun things that can be done. In order to ensure that the water in your pool is safe and clean, proper maintenance and care is essential. Besides cleaning the pool on a regular basis, you must check its alkalinity periodically. High alkaline levels can irritate your eyes and cause scale and mineral deposits on the walls and the floor of the pool. It can also turn your skin dry and itchy. This can lead to stains on the flooring and sides of the pool as well.

  1. Alkalinity has a significant impact on pH levels of the pool, but they are two separate entities.

    1.Surprise Checkups

    Building permits are needed when you are constructing a pool on your property. After that, it is your responsibility to ensure that they are maintained and secured adequately. In some areas, zoning authorities may conduct surprise inspections to ensure that your pool meets all the regulations. Failure to comply with the rules can lead to cancellation of your pool permit.


    Once you have determined what is causing the high alkalinity in your pool, you must take remedial measures to bring down the levels. Alkalinity has a significant impact on pH levels of the pool, but they are two separate entities. By controlling the alkalinity, you can ensure that the pH level stays neutral which is the suggested level for swimming pools.

  2. 2.Causes of Alkalinity

    It is common to see the alkalinity levels of pools rise periodically. There are a number of factors that lead to this. Water with high alkaline levels is known as ‘hard water’. One common cause of high alkalinity is that pool owners simply overestimate the amount of alkalinity boosters needed for the pool. This happens when trying to balance the pH level of the pool to a neutral 7. This is most often practiced in areas with frequent acid rain. The nitric acid and sulfuric acid found in acid rain increases the acidity levels of the water. In order to bring down the acidity, alkaline boosters must be added to the water. Body sweat and lotions that mix with the water in the swimming pool can also lead to higher alkaline levels. One common indication that the water in the pool is high in alkalinity is when the pool water turns cloudy.

  3. 3.How to Lower Alkalinity in Pool

    If the alkalinity level of the water in the swimming pool is higher than normal levels, it is necessary to bring it down. For this purpose, you must add some dry acid or muriatic acid to the water. While adding the acid as per instructions on the container, it is necessary to keep the pool filter switched off. Care should be taken to ensure that the acid should not be poured near any metal fittings in the pool. The pH level of the water needs to be monitored while the acid is being added. You should also look at the pool filtration and circulation equipment to ensure that it is functioning properly. You may have to repeat the treatment again in a few days.


    The pool’s lining material is significant in determining the alkalinity levels of the water. Pools that are lined with gunite require lower alkalinity than those with fiberglass or concrete. The only chemicals suitable for reducing the alkalinity of water in the pool are muriatic acid or sodium bisulfate. This is because most other chemicals are likely to raise the alkalinity level instead of reducing it. Ideally the chemicals must be added in increments to avoid sudden fluctuations in the level of alkalinity.

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