Step 2:
Optimal coagulation and
flocculation with APF and ZPM
AFM ® will remove most particles down to 5 microns
and many micron and sub-micron particles as well as
dissolved organic components. When AFM ® is com-
bined with a cavitating ZPM static mixer using APF
(All Poly Floc), the performance is greatly enhanced.
The combined system now gives nominal filtration
down to 0.1 microns that is a 50 times better filtration.
In addition, it removes most of the dissolved organic
matter and reduces chlorine oxidation demand by
up to 80 %. Why is this so important?
Less consumption of chlorine = less disinfection
by-products (DBP): Chorine must be used in all
public pools. Chlorine is an excellent disinfectant
that will kill most bacteria in less than 30 seconds.
No other disinfectant comes close, which means
chlorine is the only oxidising agent that protects
the bathers from horizontal transmission of disease.
However, a major disadvantage of chorine is that
if forms toxic disinfection by-products (DBP). This
is why it is so important to treat the water to the
highest possible standard in order to minimise the
concentration of these disinfection by-products. This
is the whole reason behind DAISY to make pools
safe but it also makes good economic and environ-
mental sense to minimise the amount of energy and
chemicals.
APF: All-poly Floc
APF is the most sophisticated and powerful coa-
gulation and flocculation product available to the
swimming pool industry. Most of the chlorine
demand is not from particles in suspension but
from chemicals in solution. APF contains different
electrolytes that drag dissolved chemicals out of
solution to form small particles.
In addition to electrolytes, APF also contains poly-
electrolytes to flocculate small particles to make
larger particles that can then be removed by AFM ®
filter media. APF imparts a positive charge on the
particles that are then adsorbed onto the negative
charged surface of AFM ® .
• Flocculation is the process of bringing the colloi-
dal suspensions of small particles (skin cells, bacte-
ria and parasites) together to form larger particles
or flocs that can be easily removed by AFM ® . APF
imparts a positive charge to the particles that are
now attracted to the negative charge surface of
AFM ® . Flocculation takes several minutes and the
particles are very fragile, which means the water
must not be subjected to aggressive agitation.
Use DIN standard filers because they give more
head space above the filter bed and hence more
time for the flocculation reactions to develop.
How to inject APF?
APF should be injected into the water using a peri-
staltic pump (for example a Dryden Aqua flocdos
pump) on a continuous basis via a ZPM before the
AFM ® filter. Diaphragm dosing pumps should not
be used because they do not provide a continuous
flow. The dose rate is 1 ml per m 3 of water passed
through the filters. The water quality will affect the
coagulation and flocculation reactions. For best
results, alkalinity as CaCO 3 should be greater
60 mg/l and the hardness above 100 mg/l.
NoPhos is one of the electrolytes in APF; every 20
litres of APF contain 0.5 litres of NoPhos and is
responsible for phosphate control in pool water. If
100 % of the phosphate is removed, then bacteria
and algae simply cannot grow. APF contains suffi-
cient NoPhos for most pools. If for any reasons
(heavy bather load or water companies adding
phosphate to municipal supplies) the Nophos in
the APF is not enough, we recommend to add 1 l
of Nophos in APF or directly to the pool water.
How does APF work?
• Coagulation is the process involving the destabili-
sation of dissolved chemicals to form a precipitate.
In order to make coagulation work, APF must be
mixed instantly and aggressively with the water –
this is why we designed the ZPM. If a ZPM is not
used, the coagulation stage is missed and APF
jumps to flocculation.
Swimming pool with strong algae attack – not with NoPhos
DRYDEN AQUA
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