Active IQ Level 2 Certificate in Leisure Operations (sample manual)

as would be the case of the backwashing of the filters, the incoming pH of the mains water may well be
different to that of the pool, and therefore the pH will change.
• pH can be raised by adding sodium carbonate
• pH can be reduced by adding an acid, for example, hydrochloric acid, sodium bisulphate, carbon
dioxide (CO 2
)
The ability of chlorine to kill bacteria is directly related to the pH of the water. As the pH increases, the
efficiency of chlorine decreases. This effectively means that the pool operator will use more chemicals if
they allow the pH to continue to run at high levels.
The following diagram illustrates the link between pH and active disinfectant within the pool. The yellow
line relates to hypochlorous acid (HOCl), which is the effective disinfectant when using chlorine and the
red line relates to hypobromous acid (HOBr), which is the active ingredient when the pool is disinfected
with a bromine compound.
At a pH of approximately 7 active disinfectant levels of hypochlorous acid are approximately 62%.
However, this drops to 22% at pH 8.
pH effect on disinfection
% 100
90
80
70
ACTIVE DISINFECTANT %
60
50
40
H0Cl
H0Br
30
20
10
0
4 5 6 7 8 9 10 11
pH VALUE
Source: Pool Water Treatment Advisory Group (PWTAG)
pH and the efficiency of disinfection
There is a link between pH and the efficiency of disinfection, in that as the pH rises, the less efficient the
disinfectant is. So, put simply, if the pH is allowed to rise, the pool operator will need to use more
disinfectant to maintain the disinfection level than they would with a pH between 7.2 and 7.4.
Copyright © 2017 Active IQ Ltd. Not for resale | 3

General principles
It is absolutely essential that the pool operator takes care to ensure that pool water testing is as accurate
as it can be. Good quality results cannot be obtained by guessing water quantities, using dirty equipment
or contaminating samples by allowing fingers to touch tablets.
Chlorine readings and pH readings are carried out with either a piece of equipment referred to as a
comparator or a piece of equipment referred to as a photometer.
The following guidance applies to both:
• test tubes and test cells must be kept clean and rinsed thoroughly after each test
• never touch the tablets with your fingers
• wash hands before carrying out water testing, this is particularly true for the photometer method
• test tubes and test cells should be fitted with rubber caps
• crushing rods, used for crushing the tablets, should be cleaned and dried after use
• discoloured test cells/test tubes should be discarded
• the shelf-life of tablets must not be exceeded
• use the correct tablets for the equipment that is being used
• pool operators must be trained in the use of the equipment used on the site
• pool water samples should be taken from the pool itself at a depth of 300mm at a point which has
been found to be typical of the chemical conditions in the pool
Comparators
The traditional method of pool water testing for pH and
chlorine is using the comparator. This is a very simple piece
of equipment where the test sample containing the reagent
dye is compared against a circular disc containing different
coloured glass.
Ideally, the comparator should be fitted with a portable backlight
which provides good quality white light to accentuate the
colour or it should be viewed against a bench-mounted white
light source.
The comparator is supplied with discs appropriate to the test being carried out, for example, pH discs
(phenol red) and chlorine discs. It is also possible to obtain a disc which will measure bromine levels.
Chlorine disc for use
with comparator
pH disc for use with
comparator
Bromine disc for use
with comparator
6 | Copyright © 2017 Active IQ Ltd. Not for resale

The Langelier method
This method requires the use of a factor table and the application of simple formula to determine the
balanced water index.
The formula is:
Langelier Index = TF + CF + AF + pH - TDSF
Where:
TF = temperature factor
CF = calcium hardness factor
AF = total alkalinity factor
pH = value (not factor)
TDSF = total dissolved solids factor
The factor table is as follows:
Temperature TF Calcium CF Alkalinity AF TDS TDSF
mg/1
mg/1
19 0.5 75 1.5 50 1.7 1,000 12.1
24 0.6 100 1.6 100 2.0 2,000 12.2
29 0.7 150 1.8 150 2.2 3,000 12.3
34 0.8 200 1.9 200 2.3
41 0.9 300 2.1 300 2.6
400 2.3
800 2.5
When the calculation is completed the results will either be positive (plus) or negative (minus). A positive
index indicates that the pool is scale forming, a negative result indicates the pool is corrosive.
An index of zero would indicate that the pool is balanced, providing that all of the tests are within the
agreed range for the tests. It is generally considered acceptable to have an index of between 0 and +0.5.
A balanced water test is normally carried out on a weekly basis. An example of how to carry out the
balanced water calculation if given below.
Test Test result Factor
Temperature 29 o C 0.70
Calcium hardness 75mg/l 1.50
Alkalinity 50 mg/l 1.70
pH 7.1 7.10
Sub Total 11.00
TDS 1000 12.10
Langelier Index -1.1
The results of the above test indicates that the pool is corrosive and therefore, out of balance.
Copyright © 2017 Active IQ Ltd. Not for resale | 11

The operator needs to count the number of tablets it takes for the colour changes to occur. In the case of
a 50ml sample, each tablet has a value of 40mg/l and having determined the number of tablets, this
number multiplied by 40 is then corrected by the subtraction of 20 from the end result.
Example - 5 tablets to achieve the colour change would be 5 x 40mg/l, which is 200mg/l minus 20
(correction factor). Result 180mg/l.
Total alkalinity test using 50ml sample,
colour change method
When measuring incoming mains water it may be useful to measure alkalinity using a 100ml sample in
which case, the formula is adjusted to 20mg/l for each tablet value, less 10 as the correction factor.
Calcium hardness is tested in exactly the same way but in this case the operator is looking for a violet
colour.
Calcium hardness test using 50ml
sample, colour change method
Total dissolved solids (TDS) levels are measured using an electronic TDS tester. For best practice TDS
levels should be maintained no higher than 1000mg/l, higher than the incoming mains water.
Typical TDS tester
Copyright © 2017 Active IQ Ltd. Not for resale | 13

It is recommended that pools should be tested for chlorine levels and pH levels:
• before the pool opens to the public
• every 2-3 hours during the hours of operation
• testing the pool at the end of the day is also good practice
The testing protocols should be included within the normal operating procedures and will take into account
bather loading, the type of the pool, the opening hours and whether or not the pool is disinfected via an
automatic dosing plant.
A pool treated with a fully automatic dosing plant which is working correctly, requires less frequent testing
than a pool which is manually dosed with chemicals. Pool Water Treatment Advisory Group (PWTAG)
guidance should be followed in relation to this.
The tests for balanced water i.e. total alkalinity, calcium hardness and total dissolved solids would normally
be carried out once per week.
The importance of maintaining swimming pool water quality
If pH or chlorine levels are out range, the pool could become unsafe.
If the pH, total alkalinity, calcium hardness or TDS levels are out of range, the pool could become
unbalanced i.e. became corrosive or scale forming.
The optimum ranges for the pool water tests are as follows.
Test
Free chlorine
Combined chlorine
Optimum range
Never lower than 0.5mg/l
Best industrial practice is based upon the minimum use of chemicals in order to ensure
bacteriological quality
Normally, pool operators tend to set free available chorine levels at 1.5mg/l for typical
swimming pools
At 5mg/l the automatic dosing plant should be switched off
At 10 mg/l or above the pool must be evacuated
This should be as low as possible. Ideally, never more than 1mg/l and half the value of
the free chlorine or less
pH Ideally should be maintained between 7.2-7.4
Total alkalinity Level is determined by the disinfectant used but will be within the overall range 80-
200mg/l
Calcium hardness
Total dissolved solids
Temperature
Never lower than 75mg/l, not higher than 500mg/l
Maintained no higher than 1000mg/l, higher than the incoming mains water
Dependent upon activity and type of pool
14 | Copyright © 2017 Active IQ Ltd. Not for resale

Pseudomonas aeruginosa
Pseudomonas aeruginosa is capable of growing in water even at relatively
low temperatures, and they can readily form colonies of bacteria in filters.
They have been associated with pool water play inflatables, plastic surfaces
and pool covers. P. aeruginosa can cause skin and ear infections, so its
presence in pool water is undesirable.
Bacteriological sampling - interpreting the results
In order to ensure that the pool is operating safely, acceptable levels for bacteria are as below.
Aerobic colony count (ACC)
The aerobic colony count (ACC) should normally be 10 or less colony forming units per millilitre of pool
water. If the colony count is above 10 cfu/ml, and it is the only unsatisfactory microbiological result,
providing the residual chlorine and pH values are within recommended range, it is recommended that the
water should be re-tested.
Total coliforms
Coliforms are sensitive to disinfectant and should be absent, in other words zero, in 100 ml of pool water.
A coliform count of up to 10 cfu/100 ml is acceptable provided that:
1. Coliforms are not found in the repeat sample.
2. The aerobic colony count is less than 10cfu/ml.
3. There are no E coli present.
4. The residual disinfectant and pH values are within recommended ranges.
E. coli
E. Coli should be absent (i.e. zero) in a 100millilitre sample. A single positive sample may be the result
of recent superficial contamination by a bather, which had not been dealt with by the disinfection process.
Under these circumstances a repeat sample should then be taken.
Pseudomonas aeruginosa
Well operated pools should not normally contain P. aeruginosa. If the count is over 10 per 100 ml repeat
the test.
Where repeated samples contain P. aeruginosa the filtration and disinfectant processes should be examined
to determine whether there are areas within the pool circulation where the organism is able to multiply.
Where counts exceed 50, pool closure should be considered.
16 | Copyright © 2017 Active IQ Ltd. Not for resale