Adding Chemicals:
Assuming
that the total alkalinity level is correct, we adjust the pH according to the
results of the pH test. Most better test kits have an acid demand test, which
allows you to calculate the amount of acid to add in order to correct the pH.
You generally need to know the volume of the pool to calculate the quantity
required.
In
general, the pH of pool water tends to rise. This is a result of chlorination,
swimmer's wastes (sweat, urine, . . .) and nature's tendency to balance the pH
of standing water at about 8.5 .
High
pH can be reduced with an acid. The
most common pool acids are:
Extreme
care must be taken when adding acid to the pool, as negligence
can result in serious burns. Before adding the acid, be sure there are no
swimmers in the water and that the pump is running. You will need a plastic
bucket to mix the acid in.
Always
add acid to water; never add water to acid!
3/4 fill the bucket with water from the pool. Add the acid to the bucket and
pour it slowly around the deep end of the pool. If
you are adding a large quantity of acid, do it in stages - DON'T
add large amounts of acid to the pool at one time. Allow the pump to circulate
the water for at least 4 hours and then test the pH again. A pH reading of
7.0-7.6 is required, with 7.2 being the ideal level.
If
you add too much acid to the pool at one time, you risk etching the walls,
corroding the pipes and pump fittings and you lower the total alkalinity of the
water.
Low
pH is increased with an alkali - this
is most commonly soda ash (sodium carbonate).
Assuming
that the total alkalinity is at the right level and the pH is correct, chlorine
can be added. The amount of chlorine to add depends on the present chlorine
level and the type of chlorine used. Refer to the manufacturers instructions for
quantity. If you need to know the volume of water in the pool, you can work it
out using our volume calculators.
As
discussed previously, chlorine degrades rapidly under the influence of UV light.
For this reason chlorine should be added only in the late afternoon or early
evening, when it can dissolve and mix thoroughly before the damaging sun's rays
can affect it.
The
chlorine should be evenly scattered/ poured around the pool or poured slowly in
front of the return flow jets to ensure rapid and even distribution.
Chlorine
should be kept at a level of 1.0-3.0 ppm to ensure sufficient sanitation. If you
are using a Pool Wizard, a level of 0.5 ppm is required. This combination will
provide a far superior sanitation to chlorine alone.
If
the pool has very high levels of contamination or there is a strong smell of
chlorine around the pool, you may need to shock treat the water. This involves
adding large quantities of non-stabilised chlorine (or non-chlorine oxidisers)
to the pool, which rapidly destroys the offending matter.
One
of the problems with our easily maintained sand filters is that they are unable
to trap dirt or foreign matter below 0.02 mm (20 microns). Cloudy water is
probably a result of these minute particles of matter if the total alkalinity,
pH, calcium hardness and TDS are all within the recommended limits.
Flocculation
(or coagulation) is the process of adding chemicals which bind or stick these
tiny particles together, resulting in larger clumps which settle to the bottom
of the pool and leave the water clear. These "clumps" can be easily
removed by vacuuming the floor of the pool.
Chlorination
or chlorine shock treatment may also clear the water, but this is both expensive
and upsets the water balance.
Flocculant
is relatively inexpensive and can be used frequently in pools that are exposed
to high levels of pollutants (both environmental and swimmer waste). Follow the
manufacturer's instructions for use, as there is a wide variety of "floc
agents" available, each of which has different directions.
If
the stabiliser test shows that the level is low (below 30 ppm), stabiliser needs
to be added. The quantity can be determined from with our stabiliser calculator.
New
pools and pools that have been drained need to be stabilised. Existing pools
usually only require a top up of cyanuric acid. Never neglect the stabiliser, or
you will waste huge quantities of chlorine.
Algaecide
The use of algaecide to prevent or destroy algae is often recommended. Its use,
however, can result in water foaming, a change in total alkalinity and pH, and
an increase in TDS. Cheaper copper-based algaecides can cause water
dicolouration, staining of the pool walls and floor, and green hair and
fingernails (see copper for more information). Algaecides that contain isolated
(chelated) copper are desirable, though they tend to be quite costly. With the
use of various sanitising units available, such as the Pool Wizard, algaecides
are not necessary. If you use an algaecide, follow the manufacturer's
directions.
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