Water Talk By: Kelley and Susan McGuiness
Water Chemistry made simple, or at least as
simple as possible
Pool and Spa Chemistry and Water Balance.
Pools and spas are great, but they can become your worst nightmare if the water
chemistry isn't up to snuff. Browse around for the information you need
and if you have any questions please feel free to E Mail us and we will try to
Our Spa Service Company
Pool and Spa Facts. This is a new
section and we hope it will help answer your questions and help others. We
take your E Mails or queries in the search engines and try to answer the
question in this Faq area.
VGBA Regulations and what you need to know.
Please read this, as, this is very important
Why these regulations are now Federal Law
It appears that this law is only for
commercial pools and not residential pools. This really angers me as this
incidence happened in a private pool, and at this point operators of commercial
facilities spend thousands to upgrade. I agree with the upgrade but it is
my wish to have all residential pools inspected and upgraded. If you have
a pool that has a single bottom drain, this could happen to you. Get it
TDS Part 2
Testing the Chlorine
Copper, Iron, and Others
Flocculation in Pool Water
Water Born Pool Illness
This is the most important area of spa
maintenance. It can happen in a day or not for a year, but when it
happens, it can get ugly. Change your spa water often. If
your water appears milky, or you cough while in the water, change it.
Let's tackle the why question first: The
most common reason for draining a spa is because the amount of total
dissolved solids in the water has reached its maximum allowable level.
As a general guideline, spas should be drained when the TDS level
reaches 2,000 to 3,000 parts per million or 1,500 ppm above the start-up
By definition, TDS is absolutely everything dissolved in the water - from
metals to chlorine to bromine, alkalinity, salts, bather waste and more.
And when the amount of these substances in the water gets too high, it
can cause a number of problems, including salty-tasting water, colored
but clear water, algae growth, metal corrosion, cloudy water, eye and
skin irritation, false test readings, coughing, and black mold.
What causes TDS levels to increase? When
water is heated, aerated and agitated - as is the case with water in
spas - the water's evaporation rate increases significantly. This, in
turn, dramatically affects the TDS levels in spa water because only the
water evaporates; anything else that may have been dissolved in the
water gets left behind.
As the water level in a spa drops, the first prescribed action is to add
make-up water. But while this water will have a relatively low TDS
level, it too will evaporate eventually, adding its share of TDS to the
remaining water in the spa. As this cycle continues, the spa water's TDS
levels will continue to climb.
TDS levels are also increased whenever the spa water is treated chemically.
For example, adding as little as 1 pound of dichlor, trichlor or bromine
tablets to 500 gallons of water can create an increase of 240 ppm to the
water's TDS level.
And it does not take long for that much dichlor to be added to the spa: In
addition to the 1 to 2 ounces of dichlor needed for regular chlorination
each week, many owners use their spas two or three times a week, each
time adding another ounce of dichlor. At this rate, it would only take
three weeks or so to raise the TDS levels by 240 ppm.
Many other common spa products also contribute to a spa's TDS count,
including algaecides, algae preventers, acid, sodium bicarbonate,
clarifiers, scale inhibitors, foam suppressants, stain inhibitors and
For example, if a spa owner adds a 2 ounce dose of a nonchlorine shock to
the water after each use, that dose alone will produce about 28 ppm of
TDS in a 500-gallon spa.
Another contributing factor here is bather waste. just 3 pints of human
sweat can produce approximately 4 grams of salt, which would add
approximately 2 ppm to the TDS of a 500-gallon spa. In the case of a
commercial spa that may handle an average of 25 bathers a day, the
amount of TDS from human sweat alone could be as much as 50 ppm every
And don't forget, bathers also bring with them residual soap, deodorant,
hair spray, suntan lotion, body oil, hair gel, laundry detergent, hand
lotion, cosmetics and other personal-care substances - all of which can
contribute to the build up of TDS.
When you consider the possible factors that could contribute to the spa
water's TDS, it's easy to see how the TDS level can climb very quickly
and why frequent draining is needed.
Now, as to how often a spa should be drained, the National Spa & Pool
Institute suggests the following formula: One-third of the spa's
gallonage divided by the average daily bather load equals the number of
days that the water can be used.
(Gallons x .33) -- bather load = days of
For example, a 1,200-gallon commercial spa
with an average bather load of 25 people a day should be drained after
16 days of use:
(1,200 gallons x.33) - 25 people = 16
days of use
For residential spas, however, most
experts would agree that draining a residential spa every three months
Signs that may tell you that your spa has TDS. One sign is
that you are constantly reading low alkalinity and adding A+ every week.
Another good sign is a milky look to the water, especially when you turn the air
on to your spa. I have found also that a sudden and incurable development
of black mold on the cover , behind the pillows, and around the controls.
And one final sign, and this is after it has gone to far is that you find
yourself coughing when you are in the spa. If you are experiencing any of
this change the water, it's better to change your water too often than not
Pool & Spa
The pH is one of the most important factors
in pool water balance and it should be tested and corrected at least every
week. pH is the measure of how acid/ alkaline the swimming pool water is. A
pH of 7.0 is neutral - below 7.0 is acidic, above 7.0 is alkaline. The pH of
our eyes is 7.2 . No wonder that the ideal pH for your pool is just that -
7.2 , and should be kept within the range of 7.0-7.6 .
What happens when the pool is too acidic?
(pH is low)
If your swimming pool is Marbelite or
plaster, the pool water will begin to dissolve the surface, creating a
roughness which is ideal for pool algae growth. A similar result occurs in
the grouting of tiled swimming pools.
Metals corrode - and this includes swimming
pool equipment, pipe fittings, pump connections, etc.
As the swimming pool walls and metal parts
corrode, sulphates are formed. These sulphates are released from the water
onto the walls and floor of the swimming pool causing ugly brown and black
Chlorine, which is used as a disinfectant
in the swimming pool water, is activated and lost to the atmosphere very
quickly. The water is not being sanitized, and we are throwing away our
money by adding chlorine when the pH is too low.
When we swim, our eyes and nose burn. Our
swimwear fades and perishes. Our skin gets dry and itchy.
What happens when the pool is too alkaline?
(pH is high)
The calcium in the swimming pool water
combines with carbonates and forms scale, just like in our kettles. This
calcification is seen most at the waterline, where it traps dust and dirt,
turning black with time.
The swimming pool water starts to become
cloudy or murky and it loses its sparkle.
The calcium carbonate has a tendency to
plate out on the sand in the swimming pool filter, effectively turning it
into cement. So your sand filter becomes a cement filter, and loses its
ability to trap dirt from the pool water.
As the pH rises, the power of the chlorine
to act on foreign particles is lost. At a pH of 8.0 the pool can only use
20% of the chlorine you put in. So 80% of it goes to waste and you would
need 5 times as much chlorine to provide the disinfection you need.
In alkaline swimming pool water, the
swimmers suffer too. Our eyes and nose burn and our skin gets dry and itchy.
By neglecting to test and correct the pH of
swimming pool water, we not only cause it to become unsightly, but we also
cause ourselves physical discomfort. In addition to this, we insist on
throwing away our hard-earned money on swimming pool chemicals that cannot
possibly be effective in that pool water.
After testing the water, the necessary
chemicals must be added to bring the pH to a level of about 7.6
Testing the chlorine
We recommend the Taylor Complete High test kit Part # K2005
When planning to buy a test kit to measure
the chlorine levels in your pool, it is important to remember that there a 3
aspects which can be measured:
Free available chlorine
(or residual chlorine) - is the amount of chlorine in the pool that can
sanitize or disinfect the water and is the important measurement for us.
- consists of undesirable, bad-smelling, irritating compounds which form
when there isn't enough free available chlorine.
Total chlorine -
is the total amount of chlorine in the water. It includes both free
available and combined chlorine.
We are interested in how much available
chlorine there is in the water - chlorine that can act on foreign substances
in the water to keep the pool clean and safe for the swimmers.
Too little chlorine
results in algal and bacterial growth, waterborne illnesses, cloudy water
and insufficient sanitation of the water.
Too much chlorine
can result in eye, nose and skin irritations. Remember, too, that the
chlorine in the pool is carcinogenic and we should aim to keep its level to
the minimum required for complete disinfection.
Test kits which use tablets rather than
liquid reagents are preferred. The tablets are easier to use and provide
more accurate results. Also make sure that the chlorine measuring tablets
are "DPD" as only these can measure the free available chlorine.
Take the water sample from at least 20-30 cm
below the surface and at least that far from the wall of the pool. Test the
water according to the test kit's instructions.
The desirable level of available chlorine in
the pool is 1.0-3.0ppm with 2.0ppm being the recommended ideal.
Add chlorine according to the test results. As a rough guide, a
pool needs about 600 grams of granular chlorine (2-3 cups) for each 13,000
Gal of water twice a week during the hot swimming season (150 grams or
1/2-3/4 cup if using a Nature 2 cartridge).
Please note that this is only a guide, and actual chlorine requirements
can only be determined by regular testing.
The total alkalinity (TA) is a measure of how
much of the alkaline substances there are in the water. In the swimming pool
water, we are concerned with bicarbonate alkalinity, which should be between
80 ppm and 120 ppm.
When the total alkalinity (TA) is within this
range, it prevents rapid pH changes and "stabilizes" the pH level.
If the TA is too low,
Marbelite and plaster walls will become etched, metals corrode, the pool's
walls and floor can stain, the water can turn green, eyes burn and we can
have pH bounce (pH rapidly going up and down, seemingly at random).
If the TA is too high,
the pH is difficult to adjust, the water becomes cloudy, the pool constantly
needs acid (according to your test kit) and the chlorine loses its
efficiency as a disinfectant.
It is recommended that you test the TA
regularly, but in practice it changes very little in a well-maintained pool.
To raise the level of TA,
we use sodium bicarbonate; it is the only chemical which will do this
without increasing the pH very much. Use the calculator to find out how much
sodium bicarbonate you need to raise the TA of your pool. Note that you
should only add sodium bicarbonate at the rate of 1 kg per 13,000 gals of
water every 4 days. Raising the TA can therefore be quite a time-consuming,
Lowering the total
is also a slow process. Acid, either liquid or dry, is added to the deepest
part of the pool with the filter off. The acid should only be added a little
at a time, diluting it before pouring it into the pool. Wait 3 days between
applications. It could take days or even weeks to reduce the TA if it is
very high. You should consult a pool professional if you have a high TA.
The quantities of hydrochloric acid and dry acid you will need can be
calculated using pool calculators.
Total hardness in the context of pool water
refers to the total mineral content of the water. This is made up of
calcium, magnesium, iron, manganese and other elements. These elements are
present in the water used to fill the pool, and the levels can increase
through the use of regular pool chemicals (e.g. chlorine composed of
calcium hypochlorite). We are interested in the calcium hardness levels.
The ideal range for
calcium hardness is 250-350 ppm.
If the calcium hardness is
too low, the water becomes corrosive and results in the etching of
the pool's surfaces. Metals corrode - and this includes pool equipment, pipe
fittings and pump connections. As a result, the pool's walls and floor can
Low calcium hardness can
easily be increased using calcium chloride. The amount needed can be
calculated using the calcium chloride calculator.
NOTE: divide the required amount of calcium chloride
into 3 parts. Add the first part and circulate the water for at least 4
hours. Test the water again and repeat the process until the desired level
If the calcium hardness is
too high, the result will be scale formation on all pool surfaces.
The filter and pipes become clogged, reducing water flow and filtration
efficiency. The water becomes cloudy and swimmers complain of eye
Reducing calcium hardness
is very difficult. Either replace some or all of the water in the pool, or add
chemicals that will keep the calcium in solution and prevent it from
depositing out. If the calcium hardness is high, we recommend that you
consult a pool professional.
Total Dissolved Solids
Total dissolved solids (TDS)
is, as its name implies, the measure of the total amount of dissolved
material in the water.
The level of TDS in the pool is influenced by
many factors; the chemicals we add to adjust the
chlorine, water hardness, alkalinity, dust,
dirt, human waste, . . . all increase its level.
The maximum acceptable
level of TDS for swimming pools is 1,500 ppm. At values above this,
we begin to notice stains in the pool. It will also reduce the activity of
any chemicals you add, preventing them from doing what they're supposed to.
The water may also become cloudy.
Unfortunately, if the TDS level is too high,
there is little that can be done to reduce it. The only practical solution
is to drain some or all of the water from the pool (depending on how high
the TDS is), and replace it with fresh water (with a low TDS). A regular
backwashing routine will help to prevent the TDS from rising too much.
Chlorine, which we use as a sanitizer in our pools, is very
unstable. The effects of the sun's UV rays and high temperatures reduces
chlorine's effectiveness and breaks it down into inactive components.
Stabilizer, or cyanuric acid, is a compound
which protects the chlorine from the negative effects of UV and heat. It not
only ensures that our pool remains clean and safe for the swimmers
throughout the day, but it also reduces the amount of chlorine we need to
add in order to maintain these levels of disinfection.
"According to research results,
pools without stabilizer lose about 90% of their total chlorine
residual on a sunny day in two or three hours.
Pools treated with 25 to 50 milligrams per liter of cyanuric acid, however,
under the same conditions, lose only 10 to 15 percent of their total
Ideally, the stabilizer should be maintained
at a level of about 50 ppm, the acceptable limits being 40-80 ppm. If you
use a stabilized chlorine product, you will need to add very little, if any,
stabilizer. To find out how much cyanuric acid your pool requires to raise
the level of stabilizer, you can use a stabilizer calculator.
Hot tub and spa owners need not worry about
this, as your sanitizer tablets contain their own stabilizer
If the stabilizer exceeds 100 ppm either
partially or completely change the water, as there is no way to decrease
Copper, Iron and others
Copper is one of nature's elements. It
is also used in the equipment and plumbing in most swimming pools. Copper, in
its free state, may also be present in cheaper algaecides.
Corrosive water (low pH, low TA, low calcium
hardness) caused by improper water balance or misuse of chemicals can cause
copper to be dissolved into the pool water. The water supply you use for
topping up the pool may also contain high levels of copper, iron and other
The maximum level for
is 1.0ppm, though lower levels are recommended. At high concentrations, the
copper deposits out of the water and onto hair, fingernails or pool walls
causing green stains. High levels of copper can also cause green water.
Iron in the pool
causes the water to turn brown or green. It can also cause staining of the
pool walls. Iron has much the same causes as copper (i.e. corrosive water or
high levels in the top-up water). The maximum level of iron is 0.3ppm
although iron-free water is desirable.
Copper and iron can
be "locked" into the water using chemicals (chelating agents). This prevents
the metal from discoloring the water or staining the pool.
manganese in the water increase the hardness and can
cause scale. See also calcium hardness.
Flocculation in swimming pool water
The clumping together of smaller particles to form larger
particals which filter out more quickly.
One of the problems with our easily maintained sand filters is
that they are unable to trap dirt or foreign matter below 0.02 mm (20 microns).
Cloudy water is probably a result of these minute particles of matter if the
total alkalinity, pH, calcium hardness and
TDS are all within the recommended limits.
Flocculation (or coagulation) is the process
of adding chemicals which bind or stick these tiny particles together,
resulting in larger clumps which settle to the bottom of the pool and leave
the water clear. These "clumps" can be easily removed by vacuuming the floor
of the pool.
Chlorination or chlorine shock treatment may
also clear the water, but this is both expensive and upsets the water
Flocculant is relatively inexpensive and can
be used frequently in pools that are exposed to high levels of pollutants
(both environmental and swimmer waste). Follow the manufacturer's
instructions for use, as there is a wide variety of "floc agents" available,
each of which has different directions.
Waterborne Pool Illnesses
Swimming pools are exposed bodies of water and are thus subject
to contamination. The contamination can be carried into the pool water by the
environment (e.g. wind, rain) or by swimmers.
There has been a dramatic increase in
infections and infectious diseases from swimming pools over the past few
years. Some strains of bacteria and viruses have built up resistance to the
chlorine we use as a sanitizer in our swimming pools. Others are destroyed
very slowly. Consequently, there has been an increasing demand for
alternative sanitizers able to quickly and effectively destroy the disease
Unfortunately, it is impossible to prevent
bacteria and viruses from entering the pool water. In swimming pools with a
high swimmer load, the level of contaminants entering the water are
especially high. Ill or recovering people are requested to abstain from
swimming, but many ignore this plea. Chlorine breaks down very fast in the
presence of high contamination and swimmer load and due to the effects of
the sun's UV rays and heat. With these factors in mind, many swimming pool
maintainers over-chlorinate the pool water in the hope that illness can be
This creates another dilemma - chlorine, too,
can cause health problems and overuse should be avoided at all costs.
Mineral water sanitizers such as the
Nature 2 can reduce
chlorine consumption by 75%, thus creating a safer and healthier swimming
Nature 2 also
effectively destroys potentially harmful bacteria, viruses and algae before
they can strike, but be aware The Nature 2 process can be very slow, and may
not keep up with your usage.
A total reliance on chlorine for swimming
pool disinfection is illogical in the light of research results. There is
unequivocal proof of the efficacy of non-chlorine additives or pool water
treatments that can supplement chlorine to create safer pool water. Elements
such as copper and silver have become widely accepted as potent
anti-bacterial and anti-viral agents. Patented products like the Nature 2
make good use of this knowledge in producing swimming pool disinfectants
able to cope with the micro-organisms that chlorine cannot destroy.
These are some of the diseases that can
result from infected pool water:
Gastroenteritis, Dysentery, Amoebic
dysentery, Cholera, Typhoid, Hepatitis A, Giardiasis, Cryptosporidiosis,
Salmonellosis, Shigellosis, Dermatitis.