Total Alkalinity Levels in Swimming Pools

by Pool Builders on 12-16-2009 in Articles

The total alkalinity for swimming pools and spas, is the measure of the ability of the water in these attractions to resist any changes in their pH levels. It is the buffer that is used in relation to the other chemicals when it comes to maintaining proper pool water chemistry. To make it a little more clearer, it is the measure of the amount of the total concentration of the alkaline substances or materials that are present in the pool water.

Because the alkaline materials found in the water contain carbonates and bicarbonates, it is an absolute must that we know the total alkalinity level of our pool water. This is especially true in all pool or installations, that have equipment that may be exposed to a corrosive environment due to alkaline water conditions. Examples of some of these installations or applications are your swimming pool pumps, your pool or spa heating systems, and your air conditioning systems. This buffering system is the chemical system that will resist any changes to your pool water whenever you add an acid or a base.

Any swimming pool or spa water that does not have any buffering capabilities, will have an uncontrollable pH. This uncontrolled or dramatic swing in the pH of your swimming pool is what we call pH bounce. In order for your pool disinfectant to stay within the required state regulation standards, you have to maintain a proper level of total alkalinity at all times. Failure to maintain this key element in your pool water chemistry will result in some serious pool water problems. Ideally the desired level for the total alkalinity in a swimming pool is between 80 and 120 ppm. Achieving and maintaining this desired level will prevent any rapid changes or pH swings.

Pool Water Problems

So what are some of the water problems that can arise from a poorly maintained pool water chemistry? Firstly, look at the problems that occur when your total alkalinity is too low. When your buffering capabilities are too low, your pool water will become very corrosive. This is a pool water problem that will cause other problems such as:

  • Your pool wall surfaces as well as the bottom will becoming etched (pitted).
  • The metal parts that are installed in your pool plumbing will become corroded. These metals will begin to dissolve back into your pool or spa.
  • The walls of your pool or spa can become stained.
  • You will get unwanted changes in your pH levels (pH bounce).
  • Your pool water chemistry is greatly effected. This can cause your pool water to turn green.

On the other hand, you can experience problems that are just as serious when your total alkalinity is too high as well. When it is too high, it will result in scaling water. Some of the pool water problems from this are as follows:

  • Clogged swimming pool filters.
  • You will experience a drop in your pool water circulation (drop in water flow).
  • Your pool or spa water will become cloudy.
  • Your pH level continues to move in an upward direction.
How to Prevent Pool Water Problems

To avoid or prevent the above mentioned pool water problems, it is highly recommended that you test the TA in your swimming pool or spa regularly. Regular testing of your TA will let you know if you have to take action/s to correct it. This can be either to lower or raise it. In the swimming pool and spa industry sodium bicarbonate is the chemical of choice for raising the alkalinity levels in swimming pools. Sodium bicarbonate is used because it will raise your TA level without greatly affecting your pH level. To add the correct dosage of this pool chemical to your pool or spa, you have to calculate it. This process can be very time consuming. This is due to the fact that you have to add the sodium bicarbonate to your pool at a rate of 1 kg per 50,000 gallons of water.

This is done every few days until the desired level of TA is reached. This procedure also involves constant testing so that you avoid adding to much sodium bicarbonate at one given time. Now there will be times when you will be required to lower the TA levels in your swimming pool or spa. Lowering your TA is just as time consuming as raising it. The pool chemicals of choice for achieving this task are Muriatic acid and sodium bisulfate. However as a safety precaution, it is highly recommended that you firstly dilute the acid with water in a bucket and then add the mixture to the deep end of your pool. The addition of the acid treatment to your pool or spa should be done slowly because lowering your TA can take a few days or weeks in some cases.

Besides, you do not want to drop your TA level too fast. You should always add the acid to the water and not the water to the acid. Your pool filtration system should be turn off during this addition as well. Again this is a calculated procedure that you have to carry out in order for you to add the correct amount of muriatic acid or sodium bisulfate. To successfully maintain your pools TA, you have to know its size and volume in order to calculate the correct dosage for the acid and bicarbonate. Once you have your correct dosage for either chemical, you can go ahead and properly correct the total alkalinity in any swimming pool or spa.

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