Watermaid WM40 Owner's Handbook Manual - page 8
15
* If the result is between -0.2 and +0.2, then the pool water is in
balance.
* If the result is lower than -0.2, then the pool water is corrosive.
* If the result is higher than +0.2, then the pool water is
scale-forming.
LANGELIER INDEX CALCULATION TABLE
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
32.0
37.4
46.4
53.6
59.0
66.2
75.2
84.2
93.2
104.0
127.4
Pool Water
Temperature
(°C) (°F)
Temp
Factor
(TF)
Calcium
Hardness
as CaCO
³
Hardness
Factor
(HF)
Total
Alkalinity
as CO
³
Alkalinity
Factor
(AF)
0
3
8
12
15
19
24
29
34
40
53
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
5
25
50
75
100
150
200
300
400
800
1000
0.3
1.0
1.3
1.5
1.6
1.8
1.9
2.1
2.2
2.5
2.6
5
25
50
75
100
150
200
300
400
800
1000
0.7
1.4
1.7
1.9
2.0
2.2
2.3
2.5
2.6
2.9
3.0
10. THE LANGELIER INDEX
The Langelier Index calculation table (below) can be used to check the water balance of a pool.
Readings of pH, water temperature, calcium hardness and total alkalinity are needed. These readings
are used to obtain the corresponding factor readings from the table (below) and then, to perform the
Langelier Index calculation. Add the pH, TF, HF and AF together. Then subtract 12.1 (K, a constant) to
give the Langelier Index reading.
For example, if pool water had the following values; pH 7.4, temperature 24°C (or 75.2°F), calcium
hardness 100 ppm, and total alkalinity 200 ppm, then the Langelier Index calculation would be worked
out as follows:
Start with pH
Add TF
Add HF
Add AF
Subtract (K=12.1)
Langelier Index =
To rectify corrosive water, the total alkalinity will need to be raised by adding sodium bicarbonate (Table
B, next page).
To rectify scale-forming water, the total alkalinity will need to be lowered by adding hydrochloric acid
(Table A, next page).
Please note: the use of sodium bicarbonate in an inert-surfaced pool (fibreglass, fibreglassed
concrete, painted concrete or vinyl-lined) is simply a waste of chemicals. The unchanging calcium
level means that the total alkalinity becomes a function of pH and water temperature and will then find
its own equilibrium with time.
The ideal water balance is:
* Water temperature of 15°C - 30°C (59°F - 86°F)
* Calciumlevel of 60 - 120 ppm
* Magnesium level of greater than 20 ppm
* Iso-cyanuric acid level 30 - 50 ppm
* Total alkalinity >150 ppm
* pH 7.4 - 7.8 for quartzon, marblesheen, pebble or tiled poolsor 7.0 - 7.6 for fibreglass, painted
concrete or vinyl-lined pools.
To maintain water in balance for marblesheen, pebbled, quartzon and tiled pools, the total alkalinity
should be greater than 150 ppm if the pH is to be kept below 7.8. Consult tables A and B (next
page) to achieve the correct total alkalinity.
+7.4
+0.6
+1.6
+2.3
-12.1
-0.2
Copyright © Watermaid Pty Ltd
6
Copyright © Watermaid Pty Ltd
WATERMAI
D
® QT & XT SERIES CELL - VERTICAL INSTALLATION DIAGRAM
IMPORTANT
:
* F
or QT & XT Cells, a
GA
S TRAP
must be installed to prev
ent the accumulation of h
ydrogen gas in the filter if the
pump ev
er fails (refer to diagr
am below)
.
*
The
Cell
must
be
installed
so
that
ALL
the
water
from
the
filter
passe
s
through
the
Cell
BEFORE
any
diversions
or breakouts to devices such as dual outlets, spa lines and pressure type cleaners.
*
The
Cell
must
be
installed
AFTER
any
heater
and
a
distance
of
AT
LEAST
1.5M
(4.9
ft)
away
from
the
heater,
as
per the configuration below, otherwise distortion to the Cell casing may occur.
* Use TYPE P PRESSURE SOLVENT CEMENT (glue).
* Ensure the SENSING TANG is positioned at the HIGHEST POINT.
*
WARNING:
Improper
installation
or
operating
the
WATERMAID®
electrolytic
chlorinator
model
WM40
without
water flow through the Cell can cause a build up of flammable gases, which can result in FIRE or EXPLOSION.
25%
50%
75%
100%
C
H
EC
K
*
WA
T
E
R
FL
O
W
*
C
ELL
CON
N
EC
T
ION
C
H
EC
K
*
S
ALT
LEVEL
*
C
ELL
A
U
TO
C
ELL
C
LEAN
PRE
S
S
PRE
S
S
FILTER
HEATER
PUMP
CELL
TO POOL
FROM POOL
PROVEN
PERFORMA
NC
E
SINCE
1971
POOL
CHLORINA
TION
WITH SAL
T
GAS TRAP
SENSING TANG