A good basic primer on swimming pool water balance and chemistry

A good basic primer on swimming pool water balance and chemistry

Understanding Water Balance

from Poolgear.com

H2Oh! – Understanding the chemical composition of a healthy swimming pool

Just imagine – your drinking water may not be good enough to swim in. After all, tap water often has high levels of minerals and low pH – two factors that can harm your pool and prevent chemical treatments from doing their job. The two most important things to remember about the health of your pool are that it must be sanitized and it must be balanced. The best way to sanitize your pool is with chlorine. Keeping your pool balanced, means keeping the five basic pool water components (pH, total alkalinity, calcium hardness, total dissolved solids and stabilizer) within their proper ranges, helps your sanitizer work more effectively. That’s why we say to achieve a healthy pool, sanitizing and balancing are equally important.

Total Alkalinity

In simple terms, total alkalinity refers to how much alkaline is in the water. But you can’t fully know the importance of total alkalinity without referring to pH, because the two go hand-in-hand. High alkaline water leads to high pH. Low alkaline water leads to low pH. For now, just remember that the average swimming pool should have an alkalinity reading of 100 ppm.

Swimming Pool Water pH Levels

Keeping your pH levels within the proper range is not only important for swimmer comfort, it’s also important for keeping your equipment and pool finish in good condition. pH refers to the acidity or baseness of your pool water. All you need to remember is that a proper pH level is around 7.4 to 7.6 on a pH test kit’s numeric scale. 0 to 7 reflects a low or acidic pH. 8 to 14 means the pool has a base pH level. Low pH readings mean your chlorine will dissipate a lot quicker. High pH levels make chlorine inactive. And that means the money you’re spending on chlorine is a waste.

Calcium Hardness

Anyone who’s ever washed their hair in hard water knows that hard water doesn’t do much for getting up a good lather. But in your pool, just the right amount of calcium is essential. Too little and your plaster can erode. Too much and your water could become cloudy, scale could form and stains might start. 200 to 400 ppm is the general range for calcium hardness, while 300 ppm is ideal for the average pool.


Stabilizer is to chlorine like your home’s insulation is to keeping in hot or cold air – it helps retain your chlorine longer just as insulation helps retain heat or air conditioning. Stabilizer is even added to some chlorine compounds to protect them from the breakdown effects of sunlight. When your stabilizer level is low, you’ll use a lot more chlorine. When it’s high, you may need to dilute your pool water to bring it back into the 40 to 100 ppm ideal range.

Total Dissolved Solids (TDS)

Like calcium, there are many other dissolved elements in pool water. Unless it’s distilled, all water contains dissolved minerals. As pool water evaporates, minerals remain behind and become concentrated. The more concentrated these minerals become, the harder it is for chemical additives to work and stains can form. If you have 3000 ppm or more of total dissolved solids or TDS, you may need to drain some water and add fresh water.

View the full size Understanding Water Balance portion of our “Pool Care Tips” manual.