Total alkalinity

What is Total Alkalinity

Total alkalinity in swimming pools is an important water parameter that measures the pool water’s ability to resist changes in pH. It’s a critical factor in maintaining balanced pool water chemistry. Total alkalinity is typically measured in parts per million (ppm) and should be within a specific range for optimal pool water quality, which is usually around 80 to 120 ppm.

Here’s why total alkalinity matters and how to manage it in swimming pools.

Total alkalinity (TA) is the measure of alkaline salts in pool water. The reason that pool technicians measure alkalinity is so it can help control the movement of pH in the water. We have a page dedicated to pH which can be found here.

How to increase and decrease alkalinity

We suggest changing the alkalinity SLOWLY.  Many pool owners will dump a full bag of buffer into the pool only to see the pH spike and unbalance the water chemistry.  Do it slow and it will save you time, money, and headaches.

Increase Total Alkalinity – If the total alkalinity is too low, you can raise it by adding sodium bicarbonate (buffer) to the pool water. Your pool shop can tell you how much is needed.

Decrease Total Alkalinity – If the total alkalinity is too high, you can lower it by adding hydrochloric acid or sodium bisulfate (dry acid). This process should be done carefully and gradually, as it can affect pH levels.

Remember, total alkalinity and pH are closely related. Adjusting total alkalinity can also have an impact on pH. Be mindful of this relationship and monitor both parameters regularly to maintain a balanced pool.

Low Alkalinity will damage your pool

One of the main reasons that TA is so important is because very low alkalinity will damage most pool surfaces. In the case of concrete pools, very low alkalinity will etch the pool surface. This will show up in two ways. First, there may be ‘sand’ at the bottom of your pool or in your filters. Second, calcium may be leaching out from the sides and bottom of your pool. If you bring up the TA by adding buffer, you will find that this sand will stop forming and your pH will stop moving about as much.

In the case of fibreglass pools, sometimes surface discolouration can occur after an extended period of very low alkalinity. Also, if you have solar heating or a heat pump, the low alkalinity will also erode the pipework and bring copper into the pool water.

total alkalinity

10 Pin Bowling & Alkalinity

Pool shops will often refer to sodium bicarbonate as ‘buffer’. This is because ‘buffer’ helps regulate the pH of your pool water. For example, when kids are learning to bowl at a bowling alley, they will put the side ‘buffers’ up to stop the ball from rolling into the gutter. The ‘buffers’ kept the ball in the lane.  Likewise, this is what sodium bicarbonate does to the movement of pH. It helps to keep pH within a certain range. This is why pool shops call it ‘buffer’.  If your pH is quickly flying off the scale high or low then low alkalinity may be the cause.

Total Alkalinity Calculator

Remember, increasing total alkalinity should be done gradually, rather than all at once. This is because adding buffer will also raise the pH of the water. When you reduce the pH of the water, the TA will also drop down again. Then when you raise the TA with buffer the pH rises again. Much like a back and forth game of tennis, this is a very frustrating cycle for some pool owners. So don’t add lots of buffer all at once! Dissolve and add one to two cups each day until the level is where it should be.

So you know exactly how much buffer you need to add, we have included a handy calculator here.

total alkalinity

Final Thoughts…

Maintaining proper total alkalinity is one of the key elements in ensuring the overall health and safety of your pool. Keeping the alkalinity within the right range will also preserve and extend the life of your pool surface.  Proper levels of alkalinity are a ‘support’ to keeping the pH balanced and a balanced pH feels great to swim in.