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Spa Chemistry 101
At first, trying to understand spa chemistry can seem like a daunt-
ing task to say the least. We intend on helping you understand spa
chemicals so that you can maintain the health of your spa at the best
level possible.
There are three basic principals to spa water chemistry.
1. Sanitize/Disinfect (kill viruses, germs, etc.)
2. Oxidize (break down organic compounds like oils and sweat)
3. Maintain slightly base (alkaline) water (pH of 7.4 - 7.6). This
controls the corrosiveness of the water, prevents excessive
scaling (mineral formation on surfaces exposed to water, and
insures that the water is comfortable to the skin.
Once you have a good understanding of the chemicals that are used in
your spa, you will be able to maintain proper water balance. Water bal-
ance is reached when all elements (pH, total alkalinity, calcium hardness
and total dissolved solids) are within their proper ranges.
The following definitions for chemicals will help you understand what
the chemical is and what it is used for:
Sanitizers
CHLORINE
- Chlorine is widely used as a sanitizer or disinfectant in pool
and spa water to kill bacteria, viruses and algae, and oxidizes ammonia
and nitrogen compounds such as swimmer waste. Its formal name is
Sodium Dichlor and is referred to as a chlorinated concentrate. Sodium
Dichlor is a fast-dissolving, granular, stabilized organic chlorine com-
pound providing either 56% or 63% available chlorine. Cyanuric acid
and/or stabilizers are added to prevent U.V. light destruction of the chlorine
by the sun.
Chlorinated concentrate produces chlorides and chloramines, which are
formed when chlorine has combined with ammonia and nitrogen in pool
and spa water. Chloramines exude a foul, “chlorine” odor and causes skin
and eye irritation.
BROMINE
– Bromine is the other commonly used sanitizer or disinfec-
tant in pool and spa water to kill bacteria and algae, and oxidizes am-
monia and nitrogen compounds such as swimmer waste. This chemical
does not eliminate swimmer waste unless it is combined with an oxidizer
(non-chlorine shock). It is very susceptible to direct sunlight, therefore is
not efficient in outdoor pools. Bromine is sometimes used as an alterna-
tive for people whom are allergic or sensitive to chlorine products.
Bromine products are available as sodium bromide and bromine tablets.
The bromide ion has no effective disinfectant or sanitizing capabilities
without the use of nonchlorine shock (potassium monopersulfate). Po-
tassium monopersulfate is added to oxidize, or activate, bromide ion to
The pH scale
goes from
0 to 14, with
zero being
extremely
acidic and 14
being extremely
base (alkaline).
Seven is
considered
neutral pH.
