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Pentair Pool Products MiniMax 250 Operating & Installation Manual: Maintenance (water Treatment)

Low nox series pool & spa heaters.
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Maintenance (Water Treatment)

Your Pentair Pool Products 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.
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.
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.
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 oxidiz-
able 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.
It is wise to test pool water regularly. Never allow
chlorine residual to drop below 0.6 ppm (parts per
million). The minimum level for effective chlorine or
bromine residual is 1.4 ppm.
pH - The term pH refers to the acid/alkaline balance of
water expressed on a numerical scale from 0 to 14. A test
kit for measuring pH balance of your pool water is
available from your local pool supply store; see Table 3.
pH Chart
Table 3.
Strongly Acid
0 1 2 3 4
Muriatic Acid has a pH of about 0. Pure water is 7
(neutral). Weak Lye solution have a pH of 13-14.
Rev. C 11-1-01
Strongly Alkaline
7 8 9
13 14
RULE: 7.4 to 7.6 is a desirable pH range. It is essential
to maintain correct pH, see Table 4.
If pH becomes too high (over alkaline), it
has these effects:
1. Greatly lowers the ability of chlorine to destroy
bacteria and algae.
2. Water becomes cloudy.
3. There is more danger of scale formation on the
plaster or in the heat exchanger.
4. Filter elements may become blocked.
If pH is too low (over acid) the following
conditions may occur:
1. Excessive eye burn or skin irritation.
2. Etching of the plaster.
3. Corrosion of metal fixtures in the filtration and
recirculation system, which may create brown, blue,
green, or sometimes almost black stains on the
4. Corrosion of copper in the heater, which may cause
5. If you have a sand and gravel filter, the alum used as
a filter aid may dissolve and pass through the filter.
CAUTION: Do not test for pH when the chlorine
residual is 3.0 ppm or higher, or bromine residual
is 6.0 ppm or higher. See your local pool supply
store for help in properly balancing your water
RULE: Chemicals that are acid lower pH. Chemicals
that are alkaline raise pH.
pH Control Chart
Table 4.
Add Soda, Ash or
Sodium Bicarbonate
"Total alkalinity" is a measurement of the total amount
of alkaline chemicals in the water, and control pH to a
great degree. (It is not the same as pH which refers
merely to the relative alkalinity/acidity balance.) Your
pool water's total alkalinity should be 100 - 140 ppm to
permit easier pH control.
A total alkalinity test is simple to perform with a reliable
test kit. You will need to test about once a week and
make proper adjustments until alkalinity is in the proper
range. Then, test only once every month or so to be sure
it is being maintained. See your local pool dealer for
help in properly balancing the water chemistry.
7.4 7.6
8.0 8.2 8.4
Add Acid
P/N 471593


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  • Ken Lobsinger Mar 14, 2016 02:53:
    none yet... this is required to see the manual.