32
Notes
1
The test has been calculated for an average heated
swimming
pool
(82°F, 28°C).
For
unheated
swimming pools, subtract 0.1 from the index value
obtained, for high temperature pools and spas, add
0.1 to the index value obtained.
2
Always keep the pH, Total Alkalinity and Calcium
Hardness levels within the limits recommended in
pool operating instructions and chemical suppliers'
recommendations. Seek specialist advice if corrosion
or scale formation is still apparent even though the
water is shown to be in a balanced condition.
Compliance
The DPD method is a published standard method in the
UK, the European Community, USA, Australia and in
many other countries. The Palintest DPD free and total
chlorine tests are approved by the USEPA as accepted
versions of the Standard Method 4500-C1-G (0 – 5 mg/l).
The Palintest photometer series has been independently
tested and has earned the European CE Mark of
Compliance for electro-magnetic compatibility (EMC).
33
Sample Dilution and Collection
When the test result is outside the concentration
range of the test, the photometer will display the '>'
symbol. In such cases it is necessary to dilute the
pool water and repeat the test. A Palintest dilution
tube (PT 512) is available to dilute samples accurately.
If the result is close to the top of the scale (eg
chlorine
above
4 mg/l
on
the
Chlorine-Free/5
or
Chlorine-Total/5 range, calcium hardness above 300
mg/l and cyanuric acid above 150 mg/l) and a more
accurate result is required, a dilution may be used to
increase the sensitivity of the test.
The following points should be observed when taking
water samples from the pool. Take pool water samples
from below the water surface. Collect in a clean plastic
bottle and fill to the neck so as to avoid unnecessary
airspace.
The free chlorine or bromine may drop during sample
storage. Other parameters such as pH and alkalinity
can also change. Samples should therefore be tested
as soon as possible after sample collection.