For water to be comfortable to swim in, it is essential that it be non-corrosive, non-scaling and correctly balanced. Water that is balanced, and healthy for the swimmer will also benefit the pool surfaces and prevent corrosion and erosion of equipment.
Water can be both corrosive and incrustations and when this happens we speak of unbalanced water, while water that does not cause these problems is called balanced water.
The signs of water corrosion will keep the water completely colored because of the colorations produced by the dissolution or change of state of the metals dissolved in the water. On the other hand, the incrustating water tends to deposit or precipitate calcium carbonate (among others), causing depositions on the surface of the pools, saturating filters, pipes, accessories, etc.
To properly balance the swimming pool water it is important to control the parameters that determine the water balance:
- Pool water pH
This is the measure of how acidic or basic the water is. Think back to high school science class, you may remember a numbered scale from 0 to 14 (see the chart shows below), with 7 being perfectly neutral, 0 being extremely acidic and 14 being extremely basic.
The perfect swimming pool water pH range is 7.4-7.6. Some people said that the range is 7.2-7.8, which is wider and a more forgiving range. This wider range is still acceptable, even though it is advisable always keeping the tighter 7.4-7.6 range as a goal. Use the wider range as a warning zone to correct the pH as soon as possible.
- Total Alkalinity:
This bring up to the capacity of the pool water to resist a change in pH. The key goal of this parameter is to be able to control the pH of the pool. The achieved it as a buffer solution, so that when materials are added to the pool that can increase or decrease the pool water pH these changes are controlled and do not generate important changes in the balance of the pool water.
When a substance that can affect the pH is added to the pool water, the total alkalinity reacted to neutralize and maintain the pH in the desired range.
Remember that total alkalinity does not determine the pH, but acts to help maintain the pH in the desired range.
- Calcium hardness
This parameter refers to the amount of calcium that is present in the pool water. The best range for Calcium hardness is 200 – 400 ppm.
To increase the Calcium hardness you will want to use Calcium Chloride. If you are experiencing high Calcium Hardness levels you will have to either drain the pool completely or partially.
To properly balance the swimming pool water, the pool water temperature should be kept between 72 degrees Fahrenheit (22° C) and 85 degrees Fahrenheit (29°C), except for special purpose therapy pools or spa pools. The air temperature for an indoor swimming pool should be conserved from 2 degrees Fahrenheit (1° C) to 5 degrees Fahrenheit (3° C) above the pool water temperature.
- Total dissolved solids (TDS):
This factor is normally the least worrisome one. TDS is the sum of all materials dissolved in the water and normally runs in the range of 250 ppm and higher. Most experts have discussed over what levels are considered too high, but there is no real lower limit. TDS is comprised of many different chemical compounds, which means that the problem of how much is too much actually depends more on what they consist of than how much there is.
Let’s say, sodium chloride or ordinary salt is extremely soluble and is therefore unlikely to cause a problem, whereas, as we have seen, calcium compounds can be a problem even at fairly low levels.
In general, when the TDS exceeds approximately 1500 ppm, problems may begin to occur.