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ALKALINITY: The discussion of the "alkaline level of water"
(relating to a high pH reading) has prompted many pool owners to confuse
pH and Alkalinity as a unified and singular water-balancing chemical.
While Alkalinity has a definite impact on pH, it is certainly not the
same as pH. A pH test will show either the acidity or alkalinity of
water, while the Alkalinity test will show the quantity of alkaline
material in the water. Some alkaline material is actually needed in the
water to achieve water chemistry-the ideal pH range is 7.2-7.8, which is
slightly alkaline.
This is a fairly confusing topic of water chemistry. But, unless you
will ever have to take a Chemistry 101 exam, it is not important to
discuss at length the differences between pH and Alkalinity. What is
important for you to know is the fact that both pH and Alkalinity play a
role in achieving and maintaining water chemistry. Therefore, both need
to be tested and adjusted on a regular basis. It is also important to
mention that Alkalinity should be adjusted first, and then pH, because
Alkalinity acts as a buffer for pH; if Alkalinity is in range, the pH is
far less likely to fluctuate.
For more specific information on Alkalinity, select from the following
topics:
TESTING ALKALINITY
LOWERING ALKALINITY
HOW TO ADD ALKALINITY DECREASER
HOW TO ADD MURIATIC ACID
FACTORS THAT LEAD TO HIGH ALKALINITY
PROBLEMS RESULTING FROM HIGH ALKALINITY
RAISING ALKALINITY
HOW TO ADD ALKALINITY INCREASER
HOUSEHOLD BAKING SODA
FACTORS THAT LEAD TO LOW ALKALINITY
PROBLEMS RESULTING FROM LOW ALKALINITY
IDEAL READING FOR ALKALINITY
TESTING ALKALINITY: Do not confuse an
alkaline-demand test with an Alkalinity test.
An alkaline test is an optional test that is only performed after the pH
test to determine how much alkaline material (pH Increaser or Soda Ash)
is needed to raise the pH from below 7.19 to between 7.2 - 7.8. This
alkaline test, then, is an extension of the pH test in order to elicit
the most accurate and telling results for pH. An Alkalinity test is
simply a test to measure the Total Alkalinity of the water. The
Alkalinity of your pool is determined by the type of your pool, your
chosen sanitizer/disinfectant/oxidizer, and your chosen shock.
There are two ways to test for Alkalinity: 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 pH and the chosen
sanitizer/disinfectant/oxidizer, as well as the Alkalinity. 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 Alkalinity 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. Many 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. It is a good idea to purchase a test kit that will also
test for Alkalinity. Here is a discussion:
The reagent to test Alkalinity is simply called an Alkalinity reagent.
A test for alkalinity is a titration test, which means it requires an
indicator reagent and a follow up reagent. Once the test block
is filled with sample water from the pool, an indicator reagent is added
to the sample, which changes the colour of the water. Then, a follow up
Alkalinity reagent is added, drop-by-drop. The number of drops to change
the colour of the water (as specified in the instructions of your test
kit) will determine the Alkalinity. Simply take the number of required
drops and multiply it by 10 to determine your Alkalinity. Here's an
example:
LOWERING ALKALINITY: If an Alkalinity test
shows the Alkalinity level to be too high, then the Alkalinity must be
lowered. There are two chemicals to lower Alkalinity-the same chemicals
that lower pH (Sodium Bisulfate or muriatic acid) will also lower
Alkalinity. If you recall from our discussion on lowering pH, the
manufacturers 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
Alkalinity is, and then read the instructions on the label to determine
the proper amount of pH Decreaser (Sodium Bisulfate) or muriatic acid to
add-again, remember that the same chemicals that lower pH will also lower
Alkalinity. If the Alkalinity of your pool is allowed to get too high,
then the Alkalinity must be lowered in increments, as all manufactures
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 sentences provide
an easy guideline:
- Typically, by adding 24 oz (1 ½ LBS) of pH Decreaser (Sodium
Bisulfate) per 10,000 gallons of water, or by adding 20 fluid oz of
muriatic acid per 10,000 gallons of water, the Alkalinity will be
decreased by 10 ppm. If the Alkalinity is extremely high, then the
Alkalinity must be lowered in increments, but again, never adding more
than 24 oz (1 ½ LBS) of pH Decreaser per 10,000 gallons of water or 20
fluid oz of muriatic acid per 10,000 gallons of water AT ONE TIME.
If your high Alkalinity 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
Alkalinity reading will cause frustration. The main reason is that most
test strips and test kits only read Alkalinity up to 180 ppm, but
Alkalinity can be much higher. You may add the specified maximum amount
per 10,000 gallons of water every 6 hours, but come back to test the
Alkalinity and still find it too high. You may have lowered the
Alkalinity from 320 ppm to 190 ppm, but since test strips and test kits
will not read this high (again, they only read Alkalinity up to 180 ppm),
it may seem as though nothing has been accomplished in lowering
Alkalinity, 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
Alkalinity level of your water. Listen to their advice, and within the
week, go back for a follow-up analysis on the computer. Once Alkalinity
is in range, monitor the Alkalinity closely and keep it within the
desired range so that you don't have to make such drastic, incremental,
and time-consuming adjustments. Also, having such a high Alkalinity can
cause structural and equipment damage.
HOW TO ADD ALKALINITY DECREASER (SODIUM
BISULFATE): "Alkalinity Decreaser" is the same chemical as pH
Decreaser-there is no chemical packaged and sold as an Alkalinity
Decreaser. 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 to lower your
Alkalinity 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 Alkalinity, Sodium Bisulfate is not
required to be diluted. When diluted, pH Decreaser may reduce the pH
without administering any major effects on the Alkalinity. 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: Muriatic acid,
which lowers pH, will also lower Alkalinity. 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 Alkalinity, muriatic acid is not required
to be diluted. When diluted, muriatic acid may reduce the pH without
administering any major effects on the Alkalinity. 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 ALKALINITY:
These factors can raise the Alkalinity of your pool water:
- Tap water in certain regions simply has a high Alkalinity level.
- Overestimating the amount of Alkalinity Increaser that is needed.
If these, or any other, reasons cause your Alkalinity 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 ALKALINITY:
If the Alkalinity 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).
- pH will be difficult to adjust.
- Eye and skin irritation.
If these, or any other, problems occur due to high Alkalinity, you
must lower the Alkalinity immediately, using either Sodium Bisulfate
(which is typically packaged and sold as "pH Decreaser," "pH Down," or
"pH Minus") or muriatic acid.
RAISING ALKALINITY: If an Alkalinity test
shows an Alkalinity level to be too low, then the Alkalinity must be
raised. There are two chemicals to raise Alkalinity, but poolmanual.com
will only endorse and recognize one of these chemicals. This chemical is
a granular product, which is typically packaged and sold as "Alkalinity
Increaser," "Alkalinity Up," or "Alkalinity Plus" (the product is also
often referred to by its scientific name, which is Sodium Bicarbonate).
Some pool professionals do recommend household baking soda to raise
Alkalinity. This is technically justifiable, because household baking
soda is a sodium bicarbonate. But, its manufacturers offer no directions
for pool use. Therefore, if you use it, then you are on your own. If the
manufacturers of household baking soda cannot provide directions, then
how can we?
Before adding any Alkalinity Increaser, read the instructions on the
label. Manufacturers will recommend varying amounts to be added 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 Alkalinity is, and then read the instructions on
the label to determine the proper amount of Alkalinity Increaser to add.
If the Alkalinity of your pool is allowed to get too low, then you must
increase the Alkalinity 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:
| |
10ppm |
25ppm |
50ppm |
75ppm |
100ppm |
150ppm |
| 5,000 |
2LBS |
3LBS |
4LBS |
5LBS |
6LBS |
8LBS |
| 10,000 |
4LBS |
5LBS |
6LBS |
7LBS |
8LBS |
11LBS |
| 15,000 |
6LBS |
8LBS |
10LBS |
11LBS |
12LBS |
17LBS |
| 20,000 |
8LBS |
10LBS |
14LBS |
15LBS |
17LBS |
23LBS |
| 25,000 |
10LBS |
14LBS |
18LBS |
19LBS |
22LBS |
29LBS |
| 30,000 |
12LBS |
16LBS |
22LBS |
23LBS |
27LBS |
36LBS |
| 35,000 |
14LBS |
18LBS |
26LBS |
28LBS |
32LBS |
43LBS |
| 40,000 |
16LBS |
22LBS |
30LBS |
32LBS |
37LBS |
50LBS |
| 50,000 |
21LBS |
27LBS |
35LBS |
38LBS |
44LBS |
59LBS |
How does the chart work:
- The TOP HORIZONTAL ROW will show the ppm values that the
Alkalinity must be raised in order to get into the ideal range.
- The FIRST VERTICAL COLUMN will show the approximate gallons
of water for your pool.
- The numbers in the boxes will show how many pounds of
Alkalinity Increaser (Sodium Bicarbonate) are needed in order to get
the Alkalinity in the ideal range.
You will need to test and determine your Alkalinity level and then
determine how much it needs to be raised (which again is noted on the TOP
Horizontal Row). Just follow the TOP Horizontal Row down and the FIRST
Vertical Column across until they meet, in order to determine how many
pounds of Alkalinity Increaser (Sodium Bicarbonate) to add in order to
get your Alkalinity in the ideal range. Let's look at an example:
Typically, a widely agreed upon maximum amount of Alkalinity Increaser
to be added at one time is 4LBS PER 10,000 GALLONS OF WATER; if you
have a 20,000 gallon pool, you can add 8LBS of Alkalinity Increaser.
But again, read the instructions on the label to make sure. Although
having a very low Alkalinity reading will cause frustration, at least
most test strips and test kits do read Alkalinity down to 0 ppm, so you
will know the absolute value of your Alkalinity level. But, if you are
adding the maximum amount of Alkalinity Increaser every 6 hours and still
testing it as constantly low, then go visit your local pool professionals
and have them test your chemicals on the computer, so that you really
will know the absolute Alkalinity level of your water. Listen to their
advice, and within the week, go back for a follow-up analysis on the
computer. Once the Alkalinity is in range, monitor the Alkalinity closely
and keep it in range so that you don't have to make such drastic,
incremental, and time-consuming adjustments. Also, having such a low
Alkalinity level can cause structural and equipment damage.
HOW TO ADD ALKALINITY INCREASER (SODIUM
BICARBONATE): 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 Alkalinity Increaser in front of the
deep end return jet-this return jet will disperse the Alkalinity
Increaser throughout the pool water. If the manufacturer of the
Alkalinity 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 Alkalinity Increaser in front of
the deep end 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 on the pool deck and be careful not to fall
into the pool. Regardless of how it is applied (diluted or broadcast),
never pour Alkalinity 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 Alkalinity Increaser.
HOUSEHOLD BAKING SODA: if you are using
baking soda to raise your Alkalinity, then you are on your own. Baking
soda is a household product that is not marketed or intentionally sold
for pool applications. Therefore, manufacturers offer no directions for
pool use. If you use baking soda, please be careful when adding it to
your pool. Household baking soda is Sodium Bicarbonate, so it is not at
all dangerous for pool use. But since manufacturers do market and sell
baking soda for pool use, and since they offer no application procedures,
poolmanual.com will not recommend household baking soda as a recommended
alternative to Alkalinity Increaser (Sodium Bicarbonate).
FACTORS THAT LEAD TO LOW ALKALINITY:
These factors can lower the Alkalinity of your pool water:
- Tap water in certain regions has a low Alkalinity level.
- Overestimating the amount of pH Decreaser or the amount of muriatic
acid that is needed-again, pH Decreaser, as well as muriatic acid,
lower both pH AND Alkalinity.
- High bather loads.
- Swimmer wastes, such as perspiration, urine, saliva, and other body
oils.
- Dirt, debris or leaves that blow into the swimming pool.
- The acidic level of rain will often lower pH, and perhaps the
Alkalinity as well.
If these, or any other, reasons cause your Alkalinity to be low, you
must raise it immediately, using Sodium Bicarbonate (which is typically
packaged and sold as "Alkalinity Increaser," "Alkalinity Up," or
"Alkalinity Plus").
PROBLEMS RESULTING FROM LOW ALKALINITY:
If the Alkalinity 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.
- "pH Bounce." Alkalinity acts as a buffer for pH. If the Alkalinity
is low, the pH will fluctuate dramatically. Yesterday, it may have been
7.0, and today it may be 7.8, and tomorrow it may be 6.8-it can change
from one extreme to the next, literally overnight.
- Minimizes the effectiveness of chlorine (or its alternative).
- Eye and skin irritation.
If these, or any other, problems result due to low Alkalinity, you
must raise the Alkalinity immediately, using Sodium Bicarbonate (which is
typically packaged and sold as "Alkalinity Increaser," "Alkalinity Up,"
or "Alkalinity Plus").
IDEAL READING FOR ALKALINITY: An ideal
reading for Alkalinity will vary due to three variables: (1) type of
pool, (2) type of sanitizer/disinfectant/oxidizer, and (3) type of shock.
Here are the ideal readings for each variable:
- Type of pool:
- Concrete
- Gunite
- Shotcrete
- Vinyl-liner
- Fibreglass
|
100-140 ppm
80-120 ppm
80-120 ppm
100-140 ppm
100-140 ppm
|
- Sanitizer/Disinfectant/Oxidizer:
- Liquid Chlorine
- Granular Chlorine (Dichlor)
- Chlorine Tablets (Trichlor)
- Bromine
- Alternatives to Chlorine-consult
the pool professionals that sold
you the alternative.
|
80-100 ppm
100-120 ppm
100-120 ppm
100-120 ppm
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- Shock:
- Calcium Hypochlorite
- Lithium Hypochlorite
- Potassium Peroxymonosulfate
|
80-100 ppm
80-100 ppm
80-120 ppm
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NOTE: "100" is either a low, mid-range, or high value for every
variable. Therefore, attempt to achieve and maintain your Alkalinity
level at or near 100 ppm.
Sola Products -
www.solaaqua.co.uk
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