Copper and Silver Ion Generator Sanitisers
The information in this section is based on the gathering
of information from sources that advocate the use of Copper and Silver ion
generators for pool sanitising. TPS has not investigated the potential
effects of these ions on human health. We strongly advise anyone
considering the use of this technology to consult a suitably qualified,
independent authority before going ahead.
Ionisers
Ionisers use a process of electrolysis (passing electric current
through water) to create metallic ions in water. If the cathode is
copper then copper ions (Cu2+) are created. Copper ions
in water inhibit algae growth. Adding copper sulphate or a copper
based algaecide makes copper ions when dissolved. Silver ions in
water kill bacteria.
Ionisers work by passing a low DC current through a set of metallic
electrodes, placed in line with the circulation system and set slightly
apart from each other. The voltage causes some of the outermost atoms of
the electrodes to lose electrons, which attempt to flow across the space
between the electrodes but instead are carried away by the flow of water.
Some systems use a copper and a silver electrode, other systems use two
copper electrodes, which produce copper ions only. Still others use a pair
of bi-metallic electrodes which produce both copper and silver ions.
Do you really need both copper and silver and at what level are they
effective? How do you control organic contaminants? How do you avoid
staining? What else is needed? Lets look at a copper/silver system and an
all copper system one at a time.
Copper / Silver Ioniser Systems
Copper/silver systems require the use of a copper test kit to indicate
ion test levels in the water. As both copper and silver ions are being
dispersed at the same time it is only necessary to check for the presence
of one to know the other. The rate of ion creation is proportional to the
ratio of copper and silver in the electrode. A Copper test is performed
much as you would test for chlorine residue. A level of copper in the
range of 0.15 through 0.20 ppM, a pH of 7.2 through 7.4 and a total
buffering of 80 - 100 ppM is recommended.
The ion level is adjusted by changing the current flow across the
electrodes using a manual dial on the control unit. pH and total
alkalinity are adjusted by traditional methods. Potassium
peroxyonosulphate can be used to get rid of organic contaminants and
removes the slimy protective bio shield that forms over algae. Chlorine
can also be used for this purpose. The dosage rate is 1kg per 70,000
litres for a permonosulfate compound (non-chlorine shock). Liquid chlorine
can be used at the rate of 600mL per 35,000 litres added in the evening so
it has gone by morning. Cyanuric acid contained in stabilized chlorine
compounds may be precipitated by silver ions. If copper stains develop a
chelating agent is recommended or can be used as a preventative.
All Copper Systems
A copper test kit is used to monitor ion levels in all copper systems.
Copper alone can control both bacteria and algae thus eliminating problems
of silver ions reacting with sunlight to form a black precipitate on pool
walls and equipment. Because this system relies on copper only for
bacteria and algae control a higher copper level is recommended. Slightly
less than 0.30 ppM in the off-season and 0.30 - 0.50 ppM during periods of
heavy use, maintaining a pH of 7.2 through 7.4 and total buffering of 80 -
120 ppM. Except when the system is first installed no oxidizer is
recommended. After the system is operating the only regular chemical
treatment is a non-polymer flocculating agent added once a month at a rate
of 240 mL per 35,000 litres (480 mL if water clouds). A chelating agent is
used to reduce the level of metals in the water and prevent staining.
Oxidation of organics is accomplished in the ion chamber where in addition
to producing ions the electrodes also electrolyse some water separating it
into two elements hydrogen and oxygen. Whether the amount of oxygen
produced in the chamber is sufficient to take care of all organic waste is
open to some question. It is therefore recommended that a chlorine residue
be maintained at 1-2 ppM with regular shock treatments with chlorine or a
non-chlorine shock. As for algae's bio-shield, we recommend brushing to
remove it, then the ioniser will take over.
Ioniser Maintenance
The residual provided by an ioniser comes from a gradual erosion of the
electrodes. This is true for copper/silver, bi-metallic and all copper
systems. Depending on the type, electrode life is estimated at one to two
years. You should remove any scale that has formed prior to the
installation of an ioniser. Properly maintained and sensibly applied an
ioniser system is capable of satisfying basic sanitation needs. By itself
an ioniser is able to deal with algae and bacteria but problems with water
balance, disposal of organics and proper filtration are not things that an
ioniser can handle by itself.
Copyright © 1996, 1997, 2002 TPS Pty Ltd
