Water Balancing

Keeping your pool properly balanced is one of your most important assignments as a pool owner.

Many things can throw the water out of balance. How often you use the pool, rain, sun, wind algae, dust debris, circulation, even which sanitizers you use. The source of fresh water (well, municipal, etc) will also affect water balance in a number of ways.

Six factors need to be monitored for their effect on water balance:
1. pH
2. Total Alkalinity
3. Calcium Hardness
4. Total Dissolved Solids
5. Temperature
6. Cyanuric Acid

When all these factors are within acceptable ranges, it is unlikely that your water will cause corrosion or scale deposits. Well-balanced water also provides maximum bather comfort. Take a water sample to your Local Pool Shop monthly for a complete laboratory analysis.

pH
Understanding pH is one of the most important aspects of pool care. Low pH can lead to skin irritation and corrosion of equipment. High pH can result in cloudy water and contribute to scale formation. More importantly, the incorrect pH will reduce the effectiveness of the chlorine in your swimming pool. Remember to check the pH at least twice a week. The ideal range is between 7.2 and 7.6

Total Alkalinity
Total alkalinity (TA) refers to the quantity of alkaline materials dissolved in water, which act as a buffer in controlling pH change. TA is an important factor that should be taken into account in optimizing water conditions.

The ideal range for TA for pools using calcium hypochlorite based primary sanitizers is 60ppm – 100 ppm and for pools using trichlor based primary sanitizers, the recommended range is between 80 and 120 ppm.

If the TA is below 60ppm the pH will not stay in the proper range and the pool water may promote corrosion and cause damage to pool fixtures and equipment. TA that is above 120 can cause cloudy water or scale.

NOTE: Cyanuric acid (stabilizer) will interfere with the test for total alkalinity, therefore it is necessary to compensate for this interference. For pools with properly maintained pH and a cyanuric acid level above 50 ppm, the correction formula is Tested Total Alkalinity Result – 1/3 Cyanuric Acid Reading = TRUE TOTAL ALKALINITY. In other words, subtract one-third of the cyanuric acid reading from the tested total alkalinity reading to compensate for the interference.

Calcium Hardness
All water contains some natural hardness, which will vary by geographic region and by source within a region. Calcium hardness (CH) refers to the calcium and magnesium content of the pool water. It is wise to test the CH levels regularly to prevent problems on the pool shell or in the circulation system. The recommended range for calcium hardness is 200 – 500 ppm (up to 1000 ppm is acceptable).

Pool water with a calcium level above 1,000 ppm may become cloudy and if left long enough will form scale on pool surfaces and fittings. CH below 200 ppm can corrode pool equipment. In plaster pools it may result in pitting or etching problems.

Testing for hardness should be done by your Local Pool Shop or Pool Maintenance Company, preferably at spring opening (or new pool opening) and once a month during the swimming season. You could also use Home Test Strips.

Total Dissolved Solids
The total dissolved solids (TDS) are the total amount of material dissolved in your pool water. Solids that are dissolved and can’t be filtered out. So the TDS level naturally goes up over time as more water is evaporated and more chemicals are added.

Although the TDS concentration has little effect on water balance, above a certain level (2000 ppm) problems may occur with water clarity and taste. Testing for TDS should be done by your Local Pool Shop or Pool Maintenance Company, preferably at the spring opening (or new pool opening)

Temperature
For the most part water temperature also has little effect on water balance. But when water temperatures stay over 32.2°C (90°F), scale formation can develop rapidly. Prevention is the easiest solution – so test the water more frequently when it’s consistently that hot.

Metals
The problem with a high metal level is the staining it causes on pool surfaces. Unwanted metals can be the result of unbalanced water.

Source water can be a primary cause of unwanted metals
Corrosive water can attract metals from exposed metallic surfaces such as ladders.
Copper-based algaecides can also be a source of metals.

Ideally, no detectable metals should be present in your pool at any time. Ask your Local Pool Shop or Pool Maintenance Company, to test monthly.

The Bottom line on Water Balancing
You’ll be a lot more comfortable in the water, and your pool and equipment will be much better protected, if you maintain well-balanced pool water. This means keeping the pH, total alkalinity (remember the effect of cyanuric acid on the true TA reading), calcium hardness, and total dissolved solids within their acceptable ranges (see table below).

Summary of recommended ranges for water balance factors

pH: 7.2 – 7.6
Total Alkalinity: 60ppm – 120 ppm [depending on your sanitizer]
Calcium Hardness: 200 – 500 (up to 1000 is acceptable)
Total Dissolved Solids: up to 2000 ppm
Copper: 0 ppm
Iron: 0 ppm

Article Source: http://www.poolife.com/pool-care/maintenance/water-balancing.aspx