MAINTAINING POOL TEMPERATURE
To maintain pool temperature, make sure that the heater switch and valves are reset to pool settings after using the spa.
ENERGY SAVING TIPS
1. Keep the pool or spa covered when not in use. This will reduce heating costs, reduce water evaporation, conserve
chemicals and reduce load on the filtering system.
2. Reduce pool thermostat to 78° F (25° C) or lower; reduce spa temperature to 100° F (38° C). This is accepted as
being the most healthy temperature for swimming by the American Red Cross.
3. Use a time clock to start the filter pump at 6 a.m. or later. The swimming pool loses less heat after daybreak.
4. For pools used only on weekends, lower the thermostat setting by 10° F to 15° F (5° C to 8° C) during the week to
reduce heat loss. A properly sized heater will restore normal temperature within one day.
5. Turn the heater off when the pool will not be used for an extended period.
6. Follow a regular program of preventive maintenance for the heater each new swimming season. Check operation of
the heater and its controls.
CHEMICAL BALANCE
POOL AND SPA WATER
Your pool heater was designed specifically for your spa or pool and will give you many years of trouble-free service,
provided you keep your water chemistry in proper condition.
Water chemistry should follow good swimming pool water chemistry practices. When using a chlorinator, install it down
stream from the heater and at a lower level than the heater outlet. Install a corrosion resistant positive seal "Check Valve",
(P/N R172288), between the heater and the chlorinator to prevent concentrated chemicals from back-siphoning into the
heater. Back-siphoning is most likely to occur when the pump stops, creating a pressure-suction differential. Do NOT
sanitize the pool by putting chlorine tablets or sticks into the skimmer(s). When the pump is off, this will cause a high
concentration of chlorine to enter the heater, which could cause corrosion damage to the heat exchanger.
Three major items that can cause problems with your pool heater are: improper pH, disinfectant residual, and total
alkalinity. These items, if not kept properly balanced, can shorten the life of the heater and cause permanent damage.
Heat exchanger damage resulting from chemical imbalance is not covered by the warranty.
WHAT A DISINFECTANT DOES
Two pool guests you do not want are algae and bacteria. To get rid of them and make pool water sanitary for swimming
- as well as to improve the water's taste, odor and clarity - some sort of disinfectant must be used.
Chlorine and bromine are universally approved by health authorities and are accepted disinfecting agents for bacteria
control.
WHAT IS A DISINFECTANT RESIDUAL?
When you add chlorine or bromine to the pool water, a portion of the disinfectant will be consumed in the process
of destroying bacteria, algae and other oxidizable materials. The disinfectant remaining is called chlorine residual or
bromine residual. You can determine the disinfectant residual of your pool water with a reliable test kit, available from
your local pool supply store.
You must maintain a disinfectant residual level adequate enough to assure a continuous kill of bacteria or virus introduced
into pool water by swimmers, through the air, from dust, rain or other sources.
Rev. C 3/2019
CAUTION
MASTERTEMP 125 Pool and Spa Heater Installation and User's Guide
Section 6. Maintenance
47