LaMotte Pool & Spa Owner's Handbook - Manual (Page 16)

Manganese is much more rare than copper or iron, but can leave behind
blackish specks on the walls and components. Pool professionals normally
recommend metal sequestering agents to remove unwanted metals before
problems start. Note: some sanitation systems use copper treatment
compounds to inhibit algae growth. When those forms of copper are
properly maintained or chelated (bound in a form that cannot fall out and
cause problems), copper can provide a useful service. Most pool stores
have ways to test for metals, but remember that the analysis may take
several minutes.
NITRATE AND PHOSPHATE
The combination of nitrate and phosphate is the building block for algae.
Fortunately, if one is eliminated the other cannot produce algae on its
own. Large amounts of nitrates can cause other problems, such as increases
in chlorine demand. For example, an enormous amount of chlorine is
added in the morning, and is gone by the afternoon. This occurrence
is more common in seasonal pools that have just been reopened because
nitrates can enter the water from leaves or debris that were recently
removed. Other sources of nitrate intrusion come from well water supplies
and localized spraying of garden or crop fertilizers.
Since nitrates can only be removed by draining the water, some
manufacturers have focused on removing the other algae nutrient,
phosphate. A variety of phosphate removal systems have been introduced
to eliminate the potential for algae. Phosphates can enter the water from
municipal water supplies (where they are used for corrosion and metal
control) and from some forms of metal sequestering agents (as the organic
phosphate called phosphonate breaks down to ortho-phosphate). By
maintaining a constant level of 1.0 ppm or higher of free chlorine in the
pool or spa, algae should normally not be a problem. If algae develops,
promptly see a pool professional.
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The ideal range for pools and spas is less than
10 ppm nitrate and less than 100 ppb phosphate.
IDEAL
RANGE!
The ideal level of metals for pools and spas
is less than 0.3 ppm for each.
IDEAL
RANGE!