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HOW DOES SWIMMING POOL SANITATION WORK?
STUDENT NUMBER: 31305470
THE CHEMISTRY BEHIND SWIMMING POOLS �1
TABLE OF CONTENT
INTRODUCTION 3
REQUIREMENTS FOR OPTIMAL POOL CONDITION 3
Water balance 3
pH 4
Total Alkalinity 5
Calcium Hardness 6
Cyanuric Acid 6
Chlorine Level 7
Total Dissolved Solid (TDS) 7
Disinfectant By-Product (DBP) 8
METHODS OF POOL DISINFECTION 9
Chlorination 9
Sodium Hypochlorite 10
Calcium hypochlorite: 10
Lithium hypochlorite: 10
Chlorine gas: 10
Chlorinated Isocyanurates 10
Comparison Between Chlorine Sanitisers 11
Bromine 11
Salt Water Chlorination 12
Ozone 13
UV Ozone Generators 13
Corona Discharge 13
Bibliography 15
THE CHEMISTRY BEHIND SWIMMING POOLS �2
INTRODUCTION
Throughout civilisation, swimming pools have been an irreplaceable part of our everyday
lives, with the first ever pool dating back to the Pakistani city settlement of Mohenjo-daro,
over 5000 years ago. ("The History of Pools", 2018). Despite its popularity across the
world, the chemistry behind swimming pool sanitation, which is a crucial step into
assuring a safe and enjoyable time for swimmers, is rarely acknowledged. This report will
explain and evaluate the complex chemical science behind the maintenance of swimming
pools.
The requirements for optimal pool condition will first be explained in order to set the
foundation for a better understanding of the report. The different methods of pool
disinfection and the chemistry behind the processes will then be analysed.
REQUIREMENTS FOR OPTIMAL POOL CONDITION
Although swimming pools are perfect for competitive and recreational purposes, water-
born amoebae and bacteria can pose serious health risks to swimmers. It is therefore vital
to maintain good pool hygiene by following the appropriate water treatment procedures.
In order to do so, a number of factors needs to be controlled and frequently tested. These
includes:
• Water balance
❖ pH level of water
❖ Total alkalinity
❖ Calcium hardness
• Chlorine level (including free chlorine and total chlorine)
• turbidity/clarity
• Cyanuric acid
• Total dissolved solids (TDS)
("Swimming pool chemistry testing frequency - Fact sheets", 2018)
Water balance
Water balance is the relationship between different chemical measurements within the
pool. Specifically, it is used to refer to the tendency of the pool water to be either “scale
forming” or “corrosive/aggressive.”(Puetz, 2018) Water that has scale forming tendencies
tend to suffer from high pH, high total alkalinity and high calcium levels (hard water).
When two or three of these factors are present, pool water will appear to be cloudy and
scales will form on pool surfaces and equipments. On the other hand, corrosive or
aggressive water behaviour is associated with the opposite chemical factors of those
above, which results in the damaging of pool walls and corrosion of equipments. As well
THE CHEMISTRY BEHIND SWIMMING POOLS �3
as being costly to repair, this may also hinder ...
