Biguanide

Biguanide is a chlorine-free pool and spa sanitizer. (You many know Biguanide under brand

names such as BAQUACIL® Chlorine-Free Swimming Pool Sanitizer and Algistat,

BaquaSpa™ Sanitizer, SoftSwim™ Bactericide, PolyClear® MaxiPolish Swimming Pool

Sanitizer and Algistat, or Revacil® Swimming Pool Sanitizer.)* Biguanide is a popular

substitute for bromine and chlorine.

The biguanide system is a 3-part system. Biguanide alone is only an effective sanitizer

against bacteria. You must also apply weekly algaecide and shock treatments. Biguanide

systems use hydrogen peroxide as a shock chemical; follow the directions of your dealer or

manufacturer.

You should keep the biguanide level in your pool or spa in the recommended range of 30 to

50 ppm (mg/L). Be sure to make the shock and algaecide treatments on a routine basis.

pH

We use pH as an index to express how acidic or basic a solution is. (The scientific definition

of pH is “the negative logarithm of the hydrogen ion concentration”.) A pH greater than 7.0

is basic, and a pH lower than 7.0 is acidic. In pools and spas, it is important to maintain the

water in the slightly basic range of 7.2 to 7.8. The National Spa and Pool Institute (NSPI),

the industry association in the United States, has set a standard of 7.2 to 7.6 as the ideal

pH.

If pH Is Low:

• The water can corrode surfaces, metal equipment or fixtures.

• Swimmers and bathers can experience discomfort from burning eyes and itchy

skin.

• The chlorine may dissipate more quickly.

• The water may cause pitting and etching of plaster surfaces.

If pH Is High:

• Calcium and metals tend to come out of solution (the opposite of dissolving) at high

pH levels, creating the potential for staining and scale formation. The calcium and

metals will actually create deposits and discoloration on pool walls and equipment.

• Swimmers and bathers can experience discomfort from burning eyes and itchy

skin.

• High pH can contribute to cloudy water

Alkalinity

Total alkalinity is the measure of the amount of alkaline buffers (primarily carbonates and

bicarbonates) in your water. These alkaline substances buffer the water against sudden

changes in pH. Total alkalinity is considered the key to water balance. It is the first

parameter you should balance when making routine adjustments to your water.

If you neglect to check the total alkalinity in your pool or spa, you may have trouble

balancing the pH. You may also notice that pH fluctuates suddenly despite your best efforts

to keep it in the ideal range. If the alkalinity is too low, anything introduced to the water will

have an immediate impact on pH. Abrupt shifts in pH can cause scaling or corrosion of

metal equipment and fixtures as well as other problems. When the total alkalinity is high,

the pH has a tendency to drift upward, causing scale to form.

Maintaining an ideal level of alkalinity will protect your pool or spa and its equipment from

the harmful effects of sudden pH fluctuations. Think of the alkalinity as training wheels: it

keeps the pH in balance without allowing it to tip too far to either side. Of course the pH can

still drift upward or downward, but that change will happen gradually as long as the

alkalinity falls within the ideal range. The ideal range of total alkalinity for pools and spas is

between 80 and 120 ppm (mg/L).

When the total alkalinity is too low, add sodium bicarbonate. If the total alkalinity is too high,

you can lower it by using muriatic acid or sodium bisulfate