Cyanuric Acid (Stabilizer)
The sun’s ultraviolet (UV) rays will make the chlorine in an
outdoor pool dissipate quickly. In fact, an ideal level of chlorine in an
“unstabilized” pool or spa can be lost in less than two hours on a bright sunny
day, due to the UV rays of the sun. Cyanuric acid acts as a “stabilizer” that
helps chlorine hold up better when exposed to the UV rays. You can think of
cyanuric acid as blocking the effect that the sunlight has on breaking down the
chlorine—kind of like a sunscreen for your pool.
You should maintain an ideal level of cyanuric acid, 30 to 50 ppm (mg/L),
to prevent rapid chlorine loss. If the cyanuric acid level is too low, you may
need to add more to the water. However, be advised that cyanuric acid will make
the pH of the water lower (more acidic), so you may have to adjust the pH
upward as well.
On the other hand, too much cyanuric acid will reduce the beneficial effect of
your chlorine, leading to stains or cloudy water. Some chlorine compounds
already contain an amount of cyanuric acid. If you are using dichlor or trichlor
as your primary chlorine sanitizer, you are already introducing cyanuric acid
along with the chlorine. If the cyanuric acid level is your pool or spa is too
high, you will need to partially drain and refill with fresh water.
When you first fill your pool or spa, test the cyanuric acid level until you
have added enough to reach the ideal range. After that, test cyanuric acid a
minimum of once a month throughout the pool season. If you are using dichlor or
trichlor, you will have to test cyanuric acid more frequently to ensure that
the level has not exceeded the upper limit.
Hardness
Water hardness occurs as an indirect side effect of various
chemical compounds. Calcium and magnesium are the two primary minerals that
make up hardness in water. Like alkalinity and pH, hardness affects the
tendency of the water to be corrosive or scale-forming. (Scale is a deposit
that forms on pool walls and equipment when the mineral content of the water is
too high.) By maintaining the ideal ranges for hardness and alkalinity, you can
keep scale formation to a minimum.
Low hardness levels require immediate attention! They can be very dangerous to
your system. Water that is not properly saturated with hardness—water in
which the hardness level is too low—will be very corrosive, causing significant
damage to metal pipes and fixtures as well as plaster. You must be sure to
balance hardness before adding any sanitizer to the water. Otherwise, the water
will become even more aggressive (corrosive); it can cause severe damage in a
short period of time.
When the hardness level is low, increase the hardness immediately to limit the
damage of corrosive water. You can increase the hardness level by adding a
chemical like calcium chloride. When the hardness level is too high, excessive
scale formation occurs, and the water may become cloudy or discolored. Elevated
pH and warmer temperatures will increase scale build-up too. If the hardness
level is too high, you can partially drain and refill with fresh water.
The ideal level of hardness for your pool or spa water is from 200 – 400 ppm
(mg/L). You should test hardness when adding fresh water, and re-test until you
have balanced the water hardness properly. After that, test hardness a minimum
of once per month throughout the season. If you use calcium hypochlorite as a
sanitizer, you need to test more frequently to ensure that the level has not
exceeded the upper limit.
Every sanitizer has two key
functions, to sanitize (kill bacteria and
all living organisms) and also
oxidize (destroy contaminants and
waste). The most popular pool and
spa sanitizer is chlorine.
Chlorine is also classified as a
disinfectant, meaning that it is
capable of killing bacteria, algae
and other organic material
instantly. All chlorine does the
same thing when it is added to the
water, regardless of the type of
chlorine added. It forms free
available chlorine. Free chlorine is the form of
chlorine that kills
bacteria, algae and disease-causing
organisms. It is the attack
dog that guards your pool against
microbiotic intruders. (In
general, you wouldn’t want a dog in
the pool, but this is an
exception.)
You must maintain free chlorine at a
sufficient level to disinfect
potential contaminants on contact.
The more chlorine in the
water, the more it can sanitize and
oxidize the water. (Remember
that sanitizing and oxidizing are
the processes that chlorine uses
to keep the water clear and clean.)
However, if the free chlorine
level gets too high, it can make the
water uncomfortable for
swimmers. The trick is to keep the
free chlorine level in the ideal
range. In a swimming pool, keep free
chlorine at a minimum of 1
ppm (parts per million) and a
maximum of 10 ppm, with an ideal
concentration of 1 to 3 ppm.
In spas the level needs to be
maintained at a slightly higher level
due to the smaller volume and higher
temperature. The minimum
level should be 2 ppm in a spa, again
no higher than 10 ppm, and
ideally 3 to 5 ppm.
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.
For more detailed advice on the
specific chemical treatment for
your pool or spa, contact Cheap Pool
Products.
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.
For more detailed advice on the
specific chemical treatment for
your pool or spa, contact Cheap Pool
Products.
Bromine is a popular pool and spa
sanitizer often used instead of
chlorine. Bromine has some distinct
differences from chlorine.
One advantage is that bromine works
better for spas / hot tubs
(with hotter water and lower water volume) than
chlorine does. On
the minus side, bromine is sensitive
to sunlight, deteriorating
rapidly when exposed to the sun. It
can also be more expensive
than chlorine. For these reasons,
bromine is less popular than
chlorine for use in outdoor pools.
There are two forms of bromine, free
and combined. Together
these two are called total
bromine. Both forms of bromine are
sanitizers, meaning that they can kill
bacteria, algae or other living
organisms in the water. Be sure to
use a test kit that measures
total bromine, since that is the
best indicator of the level of
sanitizer in your water. The ideal
concentration of total bromine in
a swimming pool is 3 to 5 ppm. The
ideal in a hot tub or spa is 4
to 6 ppm. (In spas the level should
be slightly higher level due to
the smaller volume and the higher
temperature of the water.)
You have to monitor the bromine
level continually, almost daily,
as it will fluctuate constantly.
Environmental conditions (leaves,
rain) and usage (how many folks are
enjoying the pool or spa) will
add contaminants in the water. Those
contaminants will decrease
the bromine existing in the water.
Be sure to test the bromine
before entering the water. Even if
the system is dormant or not in
use, you should test the bromine
level at least weekly to prevent
any build-up of bacteria or algae.
Total Chlorine
Chlorine in pool and spa water may be present in two forms.
It is free chlorine that does the hard work of killing bacteria and
oxidizing contaminants. (When you add a chlorine compound like Cal-Hypo or
trichlor to your pool, you are actually adding free chlorine.) When the free
chlorine combines with these contaminants, such as oils, swimmer waste and
other organic compounds, it becomes combined chlorine, or chloramines.
In pool and spa water, this form of chlorine has very little sanitizing
ability, and no oxidizing ability. You can think of combined chlorine as a
spent bullet.
Total chlorine is just the sum of both combined chlorine and free
chlorine. In other words,
(total chlorine) = (free chlorine) plus (combined chlorine)
Knowing your total chlorine and free chlorine levels allow you to calculate
combined chlorine (combined chlorine = total chlorine minus free chlorine). If
the total chlorine level is higher than free chlorine, it is obvious that
combined chlorine is present. In that case you need to shock or
superchlorinate your pool or spa. To shock the pool, you add a free chlorine
compound in an extra large dose. The high dosage of free chlorine will actually
oxidize (destroy, burn off) the combined chlorine.