|
pH: Although it is not important to understand the
chemistry of water, it is important for pool owners to understand whether
pool water is acidic or alkaline in order to understand water chemistry.
Years ago, chemists developed a system to determine the relative
acidity or alkalinity of (drinking) water. This system involves a scale -
called the pH scale - that ranges from 1.0 - 14.0, with 7.0 being neutral
(neither acidic nor alkaline).
- Any number below 7.0 represents an acidic condition of water (low
pH).
- 7.0 is neutral
- Any number above 7.0 represents an alkaline condition of water
(high pH).
Although 7.0 is considered "neutral" for drinking water, it is not
ideal for pool water. The ideal pH range is 7.2 - 7.8, which is slightly
alkaline. Therefore, for a swimming pool, the pH scale has to be revised:
- A pH level below 7.19 will be considered acidic (having a low pH)
- A pH level between 7.2 - 7.8 is ideal for a pool
- A pH level above 7.81 will be considered alkaline (having a high
pH).
TESTING pH: There are two ways to test for
Ph: test strips or test kits.
The use of test strips is really self-explanatory. Read the
instructions on the bottle for all of the "how to" instructions. Most
test strips will test for Alkalinity and the chosen
sanitizer/disinfectant/oxidizer, as well as the pH. Here are steps to
using test strips:
- Take out one test strip and then recap the bottle.
- Dip the test strip into the water (usually about 18" below the
surface of the water).
- Hold the test strip out of the water for the required amount of
time.
- Compare the colours of the test strip to the colours of the chart
on the bottle to determine if the pH reading is low, in range, or high.
- If applicable, adjust the pH.
The use of test kits is also popular. Read the instructions on the
test kit for all of the "how to" instructions. Some test kits will test
for only pH and the chosen sanitizer/disinfectant/oxidizer, while other
test kits add the capability to include Alkalinity, and perhaps certain
other chemicals. Here is a discussion:
The reagent to test pH is called Phenol Red. Phenol red is a
colorimetric test that is commonly a reagent, but a tablet is also
available. Before adding phenol red, most test kits advise to add another
reagent first-a Neutralizer. The neutralizing reagent will rid the test
sample of any chlorine or bromine (or any other alternative). If chlorine
or bromine is present in high amounts, the addition of phenol red will
turn the sample a dark purple. If this occurs, empty the sample, clean
the test block with tap water, get another sample (from 18" below the
surface), and then add the neutralizing reagent to rid the water of
chlorine or bromine. Then, you are able to add the phenol red to
accurately test the pH.
The most common application of phenol red is adding 5 drops of the
reagent, or one tablet, to the sample. Again though, read the
instructions on your test kit to make sure of the number and sequence of
drops, or the number of tablets. Then twist/turn the test block
back-and-forth (like you are turning a door knob). The sample will turn a
shade of red. Simply match the red colour of the water to the red colour
chart on the test block to determine your pH range.
Some of the better test kits offer an "Alkaline/Acid" test to be
performed after the pH test. These tests are titration tests, where
phenol red is the indicator reagent and a follow up reagent is added to
elicit a further result:
- If the pH test shows the pH to be low, an alkaline-demand
test (also called a base demand test) is performed to determine how
much pH Increaser (or soda ash) is needed to raise the pH into its
ideal range.
- If the pH test shows the pH to be high, an acid-demand test
is performed to determine how much pH Decreaser (or muriatic acid) is
needed to lower the pH into its ideal range.
Whichever test is performed - alkaline test or acidic test - the
amount of chemical to add is determined by the number of drops needed to
change the colour of the original pH test (red) to a specified colour on
the test block. For either test, read the instructions on your test kit
for all of the "how to" instructions. Once the results are found, read
the instructions on the label of the chemical so that you can add the
appropriate amount ("X" LBS per 10,000 gallons of water) and in the
appropriate manner (diluted or broadcast).
LOWERING pH: If a pH test shows a pH level
at 7.81 or higher, then the pH must be lowered. There are two chemicals
to lower pH. The first is a granular product, which is typically packaged
and sold as "pH Decreaser", "pH Down", or "pH Minus" (the product is also
often also referred to by its scientific name, which is Sodium
Bisulfate). The second is muriatic acid, which is a liquid. Before adding
any type of pH decreaser, read the instructions on the label.
Manufacturers will recommend varying amounts to add per 10,000 gallons of
water, as well as recommend varying application procedures-some say to
dilute the product in a bucket of water and then pour it into the pool,
while others say to broadcast it into the pool directly from the package.
Therefore, poolmanual.com will not attempt to allocate a universal
application. You must simply test the water, determine how high the pH is
above 7.8, and then read the instructions on the label to determine the
proper amount of pH Decreaser or muriatic acid to add. If the pH of your
pool is allowed to get too high, then you must lower the pH in
increments, as all manufacturers will indicate a maximum amount of
product that can be added per 10,000 gallons of water at one time.
Although poolmanual.com will not allocate a universal application, we
will include a guideline. Please remember, that this is only a guideline,
and we still recommend that you read the instructions before making any
additions. The following chart will provide a guideline:
Amount to be added per 10,000 gallons of water
| pH reading |
PH Decreaser |
Muriatic acid |
| 7.9 - 8.0 |
20 oz - (1 lb and 4 oz) |
16 fluid oz |
| 8.0 - 8.1 |
22 oz - (1 lb and 6 oz) |
18 fluid oz |
| 8.1 - 8.2 |
24 oz - (1 lb and 8oz) |
20 fluid oz |
| * 8.2 - 8.4 |
24 oz - (1 lb and 8oz) |
20 fluid oz |
| * 8.4 - 14.0 |
24 oz - (1 lb and 8oz) |
20 fluid oz |
Typically the maximum amount that can be added per 10,000 gallons of
water is 24 oz (1 ½ LBS) of pH Decreaser (Sodium Bisulfate) or 20 fluid
oz of muriatic acid; So, if you have a 20,000 gallon pool, you can add
48 oz (or 3 LBS) of pH Decreaser or 40 fluid oz of muriatic acid. If
your high pH reading requires more than the maximum amount to be added at
any one time, then you will have to add the chemical in increments,
allowing 6 hours between applications.
Having such a high pH reading will cause frustration. The main reason
is that most test strips and test kits only read pH up to 8.4, but, pH
can be as high as 14.0. You may add the specified maximum amount per
10,000 gallons of water every 6 hours, but come back to test the pH and
still find it too high. You may have lowered your pH from 10.8 to 8.6,
but since the test strips or test kit will not read this high (again,
they only read pH up to 8.6), it may seem as though nothing has been
accomplished in lowering pH, when in actuality, significant improvements
have been made. If this happens to you, go visit your local pool
professionals and have them test your chemicals on the computer, so that
you know the absolute pH value of your water. Listen to their advice, and
within the week, go back for a follow up analysis on the computer. Once
pH is in the ideal range (7.2 - 7.8), monitor the pH closely and keep it
in range, so you don't have to make such drastic, incremental and
time-consuming adjustments. Also, having such a high pH can cause
structural and equipment damage.
HOW TO ADD pH DECREASER (SODIUM BISULFATE):
Read the instructions on the label. Once you determine how much to add
and how it should be applied (either diluted or broadcast), pour a
portion of the pH Decreaser in front or each return jet-the return
jets will disperse the pH Decreaser throughout the pool water. If the
manufacturer of the pH Decreaser that you purchase does not require it to
be diluted, then secure yourself on the pool deck, bend down very close
to the surface of the water, and still pour the pH Decreaser in front of
each return jet. Since the granules are so powder-like, the wind
can blow them out of the pool, or worse, in your face or eyes. Therefore,
secure yourself close to the surface of the water, and be careful not to
fall into the pool.
Often, when lowering pH, Sodium Bisulfate is required to be
diluted. Without diluting, the pH Decreaser may reduce the Alkalinity
without administering any effect on the pH. Therefore, read the
instructions. Regardless of how it is applied (diluted or broadcast),
never pour pH Decreaser, or ANY chemical, into the skimmer(s).
NOTE: For an aboveground pool, reach over the wall, get close to the
surface of the water, and add the pH Decreaser.
NOTE: pH Decreaser (Sodium Bisulfate), as well as muriatic acid,
lower BOTH pH AND Alkalinity.
HOW TO ADD MURIATIC ACID: Read the
instructions on the label. Once you determine how much to add and how it
should be applied (either diluted or broadcast), pour a portion of the
muriatic acid in front of the deep end return jet-this return jet
will help disperse the muriatic acid throughout the pool water.
Regardless of how it is applied, be sure to secure yourself on the pool
deck, bend down close to the surface of the water, and pour the muriatic
acid in front of the deep end return jet. Be careful not to fall
into the pool.
Often, when lowering pH, muriatic acid is required to be
diluted. Without diluting, muriatic acid may reduce the Alkalinity
without administering any effect on the pH. Therefore, read the
instructions. Regardless of how it is applied, never pour muriatic acid,
or ANY chemical, into the skimmer(s).
If muriatic acid gets on your skin, it will burn. If this happens to
you, immediately flush your skin with water. If muriatic acid gets into
your eyes, it will severely burn. Do not rub your eyes after handling
muriatic acid. If it does get in your eyes, though, flush them with water
and seek emergency assistance immediately. This is a good time to mention
that it is a good idea to wash your hands after dealing with ANY
chemicals.
NOTE: For an aboveground pool, reach over the wall, get close to the
surface of the water, and add the Muriatic Acid.
FACTORS THAT LEAD TO HIGH pH: These
factors can raise the pH of your pool water:
- Tap water in certain regions simply has a high pH.
- Overestimating the amount of pH Increaser or the amount of soda ash
that is needed.
- Shocking the pool with Calcium Hypochlorite, with its pH value of
11.8, or shocking the pool with Lithium Hypochlorite, with its pH value
of 10.8, will raise the pH value over time.
- A high Alkalinity reading.
If these, or any other, reasons cause your pH to be high, you must
lower it immediately, using either Sodium Bisulfate (which is typically
packaged and sold as "pH Decreaser," "pH Down," or "pH Minus") or
muriatic acid.
PROBLEMS RESULTING FROM HIGH pH: If the
pH of your pool is high, these problems will occur:
- Cloudy water.
- Scale formation on the pool walls, floor, plumbing and equipment.
- Short filler runs and overall poor filtration - primarily due to
scale that is deposited inside the plumbing, which restricts water
circulation.
- Minimizes the effectiveness of chlorine (or its alternative).
- Poor chlorine (or its alternative) efficiency - high pH not only
prevents chlorine (or its alternative) from working to its fullest
capacity, but it will also cause you to use more chlorine (or its
alternative). The high level of pH actually deteriorates the chlorine
(or its alternative) before it can engage in its intended purpose.
- A greater potential for algae growth.
- Eye and skin irritation.
If these, or any other, problems occur due to high pH, you must lower
the pH immediately, using either Sodium Bisulfate (which is typically
packaged and sold as "pH Decreaser," "pH Down," or "pH Minus") or
muriatic acid.
RAISING pH: If a pH test shows a pH level at
7.19 or below, then the pH must be raised. There are two chemicals to
raise pH. The first is granular product, which is typically packaged and
sold as "pH Increaser", "pH Up", or "pH Plus" (the product is also often
referred to by its scientific name, which is Sodium Carbonate). The
second is Soda Ash, which is also granular. Manufacturers will recommend
varying amounts to add per 10,000 gallons of water, as well as recommend
varying application procedures-some say to dilute the product in a bucket
of water and then pour it into the pool, while others say to broadcast it
into the pool directly from the package. Therefore poolmanual.com will
not attempt to allocate a universal application. You must simply test the
water, determine how low the pH is below 7.2, and then read the
instructions on the label to determine the proper amount of pH Increaser
or soda ash to add. If the pH of your pool is allowed to get too low,
then you must raise the pH in increments, as all manufacturers will
indicate a maximum amount of product that can be added per 10,000 gallons
of water at one time. Although poolmanual.com will not allocate a
universal application, we will include a guideline. Please remember, this
is only a guideline and we still recommend that you read the instructions
before making any additions. The following chart will provide a
guideline:
Amount to be added per 10,000 gallons of water
| PH reading |
pH Increaser |
Soda Ash |
| 7.1 |
½ lb |
¼ lb |
| 7.0 |
1 lb |
½ lb |
| 6.9 |
1 ½ lbs |
¾ lb |
| 6.8 |
2 lbs |
1 lb |
| 6.7 |
2 ½ lbs |
1 ¼ lb |
| 6.6 |
3 lbs |
1 ½ lbs |
| 6.5 |
3 ½ lbs |
1 ¾ lbs |
| 1.0 - 6.4 |
4 lbs |
2 lbs |
Typically, the maximum amount that can be added per 10,000 gallons of
water is 4 LBS of pH Increaser (Sodium Carbonate) and 2 LBS of Soda Ash;
So, if you have a 20,000 gallon pool, you can add 8 LBS of pH
Increaser or 4 LBS of Soda Ash. If your low pH reading requires more
than the maximum amount to be added at any one time, then you will have
to add the chemical in increments, allowing 6 hours between applications.
Having such a low pH reading will cause frustration. The main reason is
that most test strips and test kits only read pH down to 6.8, but pH can
be as low as 1.0 (but, this is very rare-or at least it better be rare).
You may add the specified maximum amount per 10,000 gallons of water
every 6 hours, but come back to test the pH and still find it too low.
You may have raised a pH from 5.0 to 6.5, but since test strips and test
kits will not read this low (again, they only read pH down to 6.8), it
may seem as though nothing has been accomplished in raising pH, when in
actuality, significant improvements have been made. If this happens to
you, go visit your local pool professionals and have them test your
chemicals on the computer so that you know the absolute pH value of your
water. Listen to their advice, and within the week, go back for a follow
up analysis on the computer. Once pH is in its ideal range (7.2 - 7.8),
monitor the pH closely and keep it in range, so you don't have to make
such drastic, incremental, and time-consuming adjustments. Also, having
such a low pH can cause structural and equipment damage.
HOW TO ADD pH INCREASER (SODIUM CARBONATE):
Read the instructions on the label. Once you determine how much to add
and how it should be applied (either diluted or broadcast), pour a
portion of the pH Increaser in front of each return jet-the return
jets will disperse the pH Increaser throughout the pool water. If the
manufacturer of the pH Increaser that you purchase does not require it to
be diluted, then secure yourself on the pool deck, bend down very close
to the surface of the water, and still pour the pH Increaser in front of
each return jet. Since the granules are so powder-like, the wind
can blow them out of the pool, or worse, in your face and eyes.
Therefore, secure yourself close to the surface of the water and be
careful not to fall into the pool. Regardless of how it is applied
(diluted or broadcast), never pour pH Increaser, or ANY chemical, into
the skimmer(s).
NOTE: For an aboveground pool, reach over the wall, get close to the
surface of the water, and add the pH Increaser.
NOTE: The same application procedure exists for Soda Ash, an
alternative to Sodium Carbonate.
HOW TO ADD SODA ASH: The same techniques
apply for soda ash, as they do for pH Increaser (Sodium Carbonate). Read
the instructions on the label. Once you determine how much to add and how
it should be applied (either diluted or broadcast), pour a portion of the
Soda Ash in front of each return jet-the return jets will disperse
the Soda Ash throughout the pool water. If the manufacturer of the Soda
Ash that you purchase does not require it to be diluted, then secure
yourself on the pool deck, bend down very close to the surface of the
water, and still pour the Soda Ash in front of each return jet.
Since the granules are fairly powder-like, the wind can blow them out of
the pool, or worse, in your face and eyes. Therefore, secure yourself on
the pool deck and be careful not to fall into the pool. Regardless of how
it is applied (diluted or broadcast), never pour Soda Ash, or ANY
chemical, into the skimmer(s).
Soda ash is often used for large public swimming pools, primarily
because they use a lot of pH control due to their high bather loads.
Another reason for the popularity of soda ash, whether it is with a
commercial pool or a residential pool, is that it is fairly inexpensive
(as compared to sodium carbonate).
NOTE: For an aboveground pool, reach over the wall, get close to the
surface of the water, and add the Soda Ash.
FACTORS THAT LEAD TO LOW pH: These
factors can lower the pH of your pool water:
- Tap water in certain regions has a low pH.
- Overestimating the amount of pH Decreaser or the amount of muriatic
acid that is needed.
- Using chlorine tablets, with its pH value of 2.8 - 3.0, or using
bromine, with its pH value of 4.0, will lower pH over time.
- Using potassium peroxymonosulfate (as a non-chlorine shock), with
its low pH value of 2.3, will lower pH over time.
- High bather loads.
- Swimmer wastes, such as perspiration, urine, saliva, and other body
oils.
- Dirt, debris or leaves that blow into the pool.
- The acidic level of rain will often lower pH.
If these, or any other, reasons cause your pH to be low, you must
raise it immediately, using either Sodium Carbonate (which is typically
packaged and sold as "pH Increaser," "pH Up," or "pH Plus") or Soda Ash.
PROBLEMS RESULTING FROM LOW pH: If the
pH of your pool is too low, these problems will occur:
- Dissolved metallic parts of your pool (walls, floor, hand rails,
ladders, light fixtures, and equipment). This could even lead to
discoloured water or stains on the pool walls and floor.
- Stained and etched concrete in concrete pools.
- Stained and etched plaster in gunite or shotcrete pools.
- Stained liner in vinyl-liner pools.
- Blistering or delamination of fibreglass in fibreglass pools.
- Minimizes the effectiveness of Alkalinity controlling chemicals.
- Minimizes the effectiveness of chlorine (or its alternative).
- Eye and skin irritation
If these, or any other, problems result due to low pH, you must raise
the pH immediately, using either Sodium Carbonate (which is typically
packaged and sold as "pH Increaser," "pH Up," or "pH Plus") or Soda Ash.
Sola Products -
www.solaaqua.co.uk
|
