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DO NOT DIVE.
WATER CHEMISTRY TERMS
YOU SHOULD kNOW
Before jumping into the Swim Spa Water maintenance, here are some
terms to help you.
1. Parts per million, or ppm:
This is a form of measurement used in most pool or swim spa
chemical readings. Best described as any one million like items of equal size and make up,
next to one unlike item, but of equal size. This would be one part per million.
2. Total Alkalinity:
This is a measurement of the ability of the water to resist changes in pH. Put
another way, it is the water’s ability to maintain proper pH. Total alkalinity is measured in
parts per million from 0 to 400 plus, with 80 to 120 ppm being the best range for swim spas.
With low alkalinity, the pH will flip, or change back and forth, and be hard to control. With
high alkalinity it becomes extremely difficult to change the pH.
3. pH or potential hydrogen:
This is a measurement of the active acidity in the water, or it is
the measurement of the concentration of active hydrogen ions in the water. The greater the
concentration of active hydrogen ions, the lower the pH. pH is not measured in parts per mil-
lion, but on a scale from 0 to 14, with 7 being the neutral. In swim spas when ever possible,
a measurement between 7.2 and 7.8 is best. Whenever possible, it should be between 7.4
and 7.6. With low pH, the results can be corroded metals, etched and stained plaster, stained
fiberglass or acrylic, eye / skin irritation, rapid chlorine or bromine loss, and total alkalinity
destruction. With high pH, the results can be cloudy water, eye / skin irritation, scale forma-
tion and poor chlorine or bromine efficiency.
4. Shocking:
This is when you add either extra chlorine (superchlorinate) by raising the chlorine
level above 8 ppm, or add a non-chlorine shock (potassium monoperoxysulfate or potassium
monopersulfate) to burn off the chloramines or bromamines. A non-chlorine shock acts by
releasing oxygen in the water, which serves the same function as chlorine. The advantage to
using non-chlorine shock, is you can enter the water within 15 minutes after shocking. Using
chlorine, you must wait until the total chlorine reading is below 5 ppm. One thing to remem-
ber, a non-chlorine shock will not kill bacteria or disinfect.
5. Sequestering:
This can be defined as the ability to form a chemical complex which remains
in solution, despite the presence of a precipitating agent (i.e. calcium and metals). Common
names for sequestering chemicals are; minquest, stain and scale control, metal-x, swim spa
defender, swim spa metal gone, (etc.).
6. Filtration:
Filters are necessary to remove particles of dust, dirt, algae, etc. that are continu-
ously entering the water. If the swim spa is not operated long enough each day for the filter
to do a proper job, this puts a burden on the chemicals, causing extra expense. A spare
cartridge should be kept on hand to make it easy to frequently clean the cartridge without
the need for a long shut down. This will also allow the cartridge to dry out between usages,
which will increase the cartridge life span as much as twice. Replace the cartridge when the
pleats begin to deteriorate. Cartridge cleaning should be done a minimum of once a month.
More often with a heavy bather load.
7. Sanitizers:
This is what kills the germs and bacteria that enter the water from the environment
and the human body.
A. Chlorine
1. Only one type of chlorine is approved for swim spa use: Sodium dichlor which is
granular, fast dissolving, and PH neutral chlorine.
2. Chlorine is an immediate sanitizer.
B. Bromine (Note: Bromine use is not recommended with Eco Pur filters.)
1. Two types of tablets.
a. Hydrotech
b. Lonza
2. Bromine is a slow dissolve chemical and may take a few days to develop a reserve
or reading in the water.
