Balancing pool water is one of the most important steps to keeping it clean and comfortable for all swimmers. You have to test your water to be sure that it is correctly balanced. You should also be aware of basic pool balancing terms that are tested so that you can understand what chemicals you may need to add to your pool water to keep it clear.

There are a few chemical factors that need that need to be in balance to maintain clear water. The word “balance” simply refers to the tendency of the water to form scale, or possibly corrosive or aggressive.

Water Testing Kit


pH is one of the most important chemical factors in swimming pools. It refers to the degree of activity of an acid or base in the water. It is measured on a scale from 0-14, with 7 being neutral. Ideally, you should test it weekly to be sure it’s kept between 7.2 and 7.8. If your water is too acidic, your pool surface and equipment can experience corrosion. If the water measures closer to the base side, you could experience scaling and cloudy pool water. When your pH is measuring correctly, the chlorine in your pool will be used at its potential.

The pH of your pool should be tested and adjusted 2-3 times weekly. 

Water pH Chart

If the pH of the pool water drifts to the acid side of the scale, corrosion of pool surfaces and equipment can occur.  If the pH of the pool water drifts to the base side, scaling, deposits, and cloudy water can occur.

Return to top

Total Alkalinity

Total alkalinity or “TA” refers to the ability of the pool water to resist change in pH. To prevent the pH from fluctuating, these acid buffers must be maintained in the pool. When a substance is added to pool water that could affect the pH, total alkalinity will react to neutralize it. TA should be tested weekly and is best kept in the range of 80-120ppm.

When reducing total alkalinity, it is best to add small amounts of acid, either liquid or dry, over a period of several days as opposed to making large adjustments rapidly. Adding too much acid at once may result in lowering the pH so severely that corrosion of pool surfaces and equipment may result. When raising total alkalinity, an alkalinity increaser is the chemical of choice and the required amount can be added all at once.

Return to top

Calcium Hardness

The amount of calcium dissolved in water is referred to as calcium hardness. When calcium is low, plaster finish could experience etching and the life of vinyl liners could be reduced. Low calcium can also affect metal fittings, causing stains to appear on surfaces from corrosion. If the calcium is too high, deposits can appear on surfaces and equipment.

The proper range for calcium hardness in pool water varies with the type of pool that you have. For concrete pools, calcium hardness should be in a range of 200-250ppm. If you own a vinyl pool, the range should be between 175-225ppm.

To raise the level of calcium in pool water, hardness increaser can be added. Reducing the level of calcium in a pool is a bit more difficult and must be done through dilution with water of a lesser hardness.

Return to top

Total Dissolved Solids

Simply put, total dissolved solids (TDS) refers to the measure of the total amount of dissolved material in swimming pool water. When the level of TDS exceeds 1500ppm, problems could occur. At elevated levels, TDS can lead to cloudy or hazy water, difficulty in maintaining water balance, reduction in sanitizer activity and possibly foaming. One of the only ways to reduce total dissolved solids is to drain some of the water and replace it with fresh water. Backwashing your pool filter regularly could prevent TDS from rising too much.

Return to top

For more information, visit Balancing.