Total alkalinity

If your pool is using lots of acid and you pH is always climbing fast, then low total alkalinity may be the problem.

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.

Buffer

Controlling the TA helps to keep the pH of the water in balance. 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. Remember, this is what sodium bicarbonate does to the movement of pH. It helps to keep pH within a certain range. Pool shops will often refer to sodium bicarbonate as ‘buffer’.

Total Alkalinity Calculator

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

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.

Low Alkalinity will damage the 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 you 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.