Polaris Watermatic C-660, User Manual, Page: 20 / 31

X. Guidelines for Using ORP for Water
Maintenance
Q. Why should I maintain a pH level between 7.2 and 7.8?
A. pH levels below 7.0 can cause eye irritation, metal corrosion,
etching of plaster, stains, damage to vinyl liners, and loss of
sanitizer. In addition to eye irritation, pH levels above 8.0 can
cause cloudy water, scale formation and loss of sanitizer effi-
ciency (low ORP).
Q. How do I increase the pH level?
A. Small amounts of basic (alkaline) chemicals such as pH Plus or
pH Up can be added.
Q. How do I lower the pH level?
A. Small amounts of liquid or dry acid (muriatic) such as pH Minus
or pH Down can be added.
Q. How does 650 mV relate to the ppm of chlorine?
A. Pure water, without conditioner, at a pH level of 7.5 corresponds
to approximately 1.5 ppm of chlorine. Actual pool or spa water
usually takes at least 1-2 ppm of chlorine to generate 650 mV
ORP (although the Total Dissolved Solids and pH can affect the
activity of the chlorine and thus change the level of ORP).
Q. Does an ORP of 650 mV stop algae?
A. No. Because algae is a living organism that adapts genetically
to a constant level of sanitizer, the periodic addition of an algi-
cide or shocking may be necessary. Please note that the addi-
tion of some chemicals can change the ORP readings for up to
several days.
Q. What causes a low ORP?
A. A low sanitizer level, a pH level above 8.0, a conditioner level
above 200 ppm or a TDS (Total Dissolved Solids) above 3,000
ppm can all cause a low ORP.
Q. How do I make sure the ORP sensor is working properly?
A. Watch the sensor reading when adding sanitizer. If it does not
respond properly, follow the recommended sensor tip cleaning
procedures on page 16. If cleaning does not solve the problem,
check the sensor as outlined on page 16.
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