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Calorex Heat Pumps Ltd. · The Causeway, Maldon, Essex CM9 4XD, UK
Installation Manual
PPT8/12/16/22LX/LY SLIMLINE
SD638150 ISSUE 11
®
4.0 Electrolytic Corrosion
in Swimming Pools
Electrolytic corrosion will occur when dissimilar metals that are in contact
with each other create a potential difference between themselves. Sometimes
separated by a conductive substance known as an electrolyte, the dissimilar
metals will create a small voltage (potential difference) that allows the ions of
one material to pass to the other.
Just like a battery, ions will pass from the most positive material to the more
negative material.
Anything more than 0.3 volts can cause the most positive material to degrade.
A swimming pool with its associated equipment can create this effect. The
pool water being an ideal electrolyte and components of the filtration circuit,
heating system, steps, lights etc providing the dissimilar metals needed to
complete the circuit.
Whilst these small voltages are rarely a safety threat, they can create
premature failure through corrosion. Not dissimilar to corrosion through
oxidation, electrolytic corrosion can cause complete failure of a metallic
material in a very short period of time.
In order to prevent this type of corrosion all metallic components in contact
with swimming pool water should be bonded together using 10mm² bonding
cable. This includes non-electrical items such as metal filters, pump strainer
boxes, heat exchangers, steps and handrails. It is highly recommended that
bonding be retrofitted to existing pools, which may not be protected by this
system.
