Do You Sustain Pool Balance With Vital Equilibrium of Chemicals?
Maintaining the chemical balance of the water is probably the single most important part of keeping a healthy pool. Unbalanced pool water will wear down your equipment, solar blanket and pool cover.
To maintain proper water balance, you will need to test for the following:
- Total alkalinity / pH balance
- Calcium hardness
Importance of Pool Balance is Directly Related to the pH Balance
pH is a measure of how acidic a solution is. It is measured on a scale from acidic (1) to the basic or alkaline (14). The pH level of pool water varies widely from 6.8 to 8.4, but the water feels most comfortable against the skin in the 7.4 to 7.6 range. ( The human eye has a pH of 7.5 ).
Generally if the pH is less then 7 it is considered corrosive. Above 8 it is too alkaline and likely to cause scaling.
Salt systems don’t preclude the need to test pH so continue to test even if you have one of these systems in place.
You can test the level of pH by one of 2 methods using :
- a pH volt meter, or
- an organic mildly acidic dye such as phenol red.
The results of a pH meter are straightforward. They are a measure of voltage generated between two electrodes.
Analyzing phenol red strips is more difficult. The dye changes colour depending on whether the water is more or less acidic. It turns orange and then yellow as the level of acidity goes up. The strip is then compared to a graduated scale that shows what pH level each colour represents. However it is possible to misread the colours depending on lighting. For the best results, you should make your comparison in bright natural light.
You should also be aware that at the extremes, the colours stop changing. So if the pH level of the pool water is lower than 6.8 it will register the same as a pH of 6.8.
Finally, chlorine can make the phenol red dye turn purple, so if the chemical balance of the pool is off, the pH test results may be impossible to read.
- Note: If the pH is too low, the sanitizer in your water will dissipate quickly.
Total Alkalinity is Directly linked with your Pool Balance
Total alkalinity (TA) measures the resistance of pH to change. Its a good indicator of how corrosive the water is. Getting the balance wrong can lead to increased deposits of scale.
You can test the TA with a titration of sulfuric acid and an acid-base indicator such as bromocresol green and methyl red. When the indicator is added to a water sample, the water normally turns green. As the sulfuric acid titrant is added, the pH level drops (becomes more acidic) and the water turns red.
Chlorine in the water can bleach out the methyl red, leaving only the bromocresol green and causing a false reading. In that case, the bromocresol green should turn blue and shift to yellow as the sulfuric acid is added.
Cyanuric acid in the water can also falsify the reading, making the water appear too alkaline.
Adjusting pH and TA to Ensure Pool Balance
You can raise the level of your pH and the TA by adding a pH increaser (TA plus) such as sodium carbonate
Lower the levels with a pH decreaser (TA minus) such as sodium bisulfate.
- Note: If your TA level is very high, you may need to use muriatic acid to lower it. Caution should be used as this chemical is very dangerous and can damage pool liners, metal and plaster.
Calcium Hardness Affects Your Pool Balance
Water contains calcium. When calcium levels are low, water draws calcium from its environment leading to corrosion of metal surfaces and pitting of concrete walls. When calcium levels are high, the calcium precipitates out, leaving hard deposits of calcium carbonate or scaling. Either way, the effect can be extensive damage.
The proper amount of calcium varies from 175 to 400 ppm.
The test for calcium hardness begins by adding sodium hydroxide to a water sample. This counters the effect of magnesium in the water which can also make it hard. An organic dye is then added to turn the water red. EDTA is then added, binding with the calcium and turning the sample blue. The amount of EDTA added indicates the water’s hardness.
To decrease the level of calcium hardness, in many cases you only need to add water. However, if your water is very hard, you may need to consult a pool professional.
To increase the calcium hardness, add calcium chloride, following the instructions on the label carefully!
Sanitizers kill bacteria. The most common are chlorine and bromine with chlorine being most widely used. Chlorine comes in granular, liquid or tablet forms.
Ideally sanitizers are used at 1 to 3 parts per million or milligrams per litre (mg/l).
Q. How often should I test my water?
A. Unless you are correcting a water problem, once a week is a good practice.