POOL CHEMISTRY
The number of chemicals related to pool water chemistry overwhelms
many new pool and spa owners. This section is designed to give you
some basic information regarding pool chemicals, and how they factor
into achieving total water balance. Many of the
facets of water chemistry, such as calcium hardness, stay at consistent
levels once properly adjusted; therefore, our recommendation is
to have a water test done at the beginning of the season.
Before we dive into the chemistry lesson, here are a few helpful
reminders to keep your pool water crystal clear all summer long:
Get into a routine. Find a time during
the week (like Sunday evening) you’re most likely going to
be home for on a regular basis. This will help ensure regular water
treatment.
Stay ahead of the game. It is important
to recognize potential problems and to treat them early. For instance,
hot weather depletes chlorine and allows for algae growth. When
experiencing a particularly hot week in the summer, it makes sense
to increase the dosage of chlorine even when the water appears to
be clear.
Chemicals provide balance. People sometimes
misunderstand that the primary purpose of adding chemicals to pool
water is to create healthy water. Adding chemicals to your water
doesn't necessarily create an unhealthy chemical environment, nor
does it 'overchemicalize' the water. Instead, chemicals are added
in order to accomplish balanced and safe water.
Weather affects water balance and uses up chemical.
Rain, algae, and dust cause pH change and eats up sanitizer. Bather
waste and some environmental chemicals have the same effect.
The Saturation Index
When we talk about water balance, we are measuring the relationship
between different factors that are key in deciding the overall healthiness
of your pool water. The Saturation Index is a mathematical equation
that measures the temperature, pH, total alkalinity, and calcium
hardness of water in order to predict whether the water is scale
forming, neutral or corrosive. All of these factors have a recommended
range for pool usage, and it is only when all of these factors are
within their prescribed ranges that true water balance can be achieved.
- Total Alkalinity - TA is the total
amount of alkaline materials (carbonates, bicarbonates, hydroxides)
present in the water. TA is a buffer for pH, meaning that it controls
the pH’s ability to change. TA and pH have a positive relationship
with one another. If the total alkalinity is too high, then the
pH will most likely remain too high and difficult to adjust. Conversely,
if the total alkalinity is too low the pH will stay below respectable
ranges and fluctuate excessively. The acceptable range for TA
in vinyl, painted, or fiberglass pools is 80-120 ppm. Use Bioguard
Balance Pak 100 to raise total alkalinity, Low N Slo to lower
it. Always have a test done before adding these chemicals.
- Calcium Hardness - CH refers to the
amount of calcium dissolved in the water. Water that is low in
calcium can cause corrosion of pool equipment and surfaces. Water
high in calcium has a tendency to form scale; thus, damage to
pipes, filtration and heating systems and pool surfaces (vinyl
liners) can result. Hard water also depletes chemical effectiveness.
The acceptable range for CH in vinyl, painted and fiberglass pools
is 175-225 ppm. Raise CH using Bioguard Balance Pak
300. When calcium hardness is too high, the only
way to lower it is through dilution of water. Always use Bioguard
Scale inhibitor as a preventative.
- Temperature - Temperature controls
the solubility of minerals in the water.
- Total Dissolved Solids- TDS for short;
it is the measure of dissolved materials in water. Pools with
high solids TDS become more susceptible to cloudiness, and can
develop a foul odour. Sanitizer effectiveness can become greatly
impeded when TDS is high. Levels should not increase above 2000
ppm.
- pH - pH is the measure of the water’s
acidity or basicity (alkalinity). The pH scale measures from 0
to 14, with 7 being neutral. The numbers on the scale are symbolic
representations for an exponential scale (i.e., a pH of 7.2 is
10 times more acidic than 7.4, 100 times more acidic than 7.6,
etc.). Low pH causes faster chlorine loss, wrinkling of liners,
eye irritation, and chloramine formation (chloramines are byproducts
of chlorine after organic waste is consumed, causing pungent smell
and skin irritation). Water with high pH is cloudy, scale forming
and inhibits chlorine effectiveness. The acceptable range for
pH in pools is 7.2-7.6. Use Bioguard Balance Pak 200
to raise pH, and Low N Slo to lower
it. *Remember to add such chemicals repeatedly over a long period
of time in small quantities so as to reduce pH bounce.
Other Factors Important in Chemical Balance
Stabilizer – Also known as cyanuric
acid, stabilizer acts like sunscreen for chlorine. When maintained
around 40 ppm, stabilizer helps reduce chlorine loss by virtue of
blocking out the sun’s UV rays. CYA remains in pool water
unless a significant amount of water is lost, or a drain and refill
occurs. While acceptable amounts of this product aid in the sustenance
of chlorine, high levels inhibit chlorine effectiveness. Pools using
bromine do not require stabilizer.
Sanitizer
– The two most popular forms of pool sanitizer
are chlorine and bromine. Most often, proper sanitization is the
result of using concentrated pucks alongside a regular shocking
(also called ‘superchlorination’) regiment. During hot
summer months, one can expect to shock pool water one or two times
per week. Heavy usage also dictates how much santizer demand your
pool will have. One common question is "when is the best time
to shock my pool?" The answer simply: at night. On a practical
level, you should not use your pool when concentrations of chlorine
are high, so it makes sense to shock the pool when no one will be
using it. Moreover, the sun’s UV rays burn chlorine. Therefore,
if you shock your pool during the day, you will be wasting chemical.
There are two measurements of chlorine that affect water balance.
Free chlorine is the amount of available, unused chlorine present
in the water. Combined chlorine refers to the amount of chlorine
still present in the water that has combined with organic waste
and become inactive. Shocking the water rejuvenates combined chlorine
back into usable chlorine. Combined chlorine contains copious amounts
of Chloramines, the gas responsible for giving your water "that
pool smell." Pool water characterized by poor odour often means
that the pool is improperly sanitized, and that it needs to be shocked.
Bromine contains similar byproducts called Bromamines, but its odour
is less pungent. Some professionals assert that bromine is a better
sanitizer because it smells less, but in reality a properly cared-for
chlorine pool should never smell either. However, bromine has proven
a healthy alternative for those who suffer from sensitive skin or
allergies to chlorine. Bioguard’s Burn-Out
and Burn-Out 35 are excellent shocking
compounds.
Algaecide – Algae comes in different
textures and colours, with green algae being the most prevalent.
It is important to add an initial dosage of algaecide as part of
a pool opening treatment, and to add regular weekly maintenance
dosages thereafter. Algaecides serve the main purpose of preparing
chlorine to battle live algae more effectively. Bioguard’s
Back-Up is an excellent maintenance algaecide; however,
if algae is present in pool water, it is recommended to have a water
test done and to add more concentrated forms of algaecide such as
Poly-guard and Erase.
Metals – Certain metals have the
ability to permanently damage pool surfaces through staining. The
preferred level for metals in pool water is therefore none. Metals
commonly found in water are iron and copper and to a lesser extent
manganese. Though not a common problem, simple tests can check for
their presence. The presence of any one of these metals can create
colour change on surfaces and in the water itself. Use a quality
stain inhibitor, such as Bioguard’s Pool Magnet
as a means of stain prevention.
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