LaMotte Pool & Spa Owner's Handbook - Manual (Page 22)

SCALE FORMATIONS
Crusty, white deposits on pool surfaces signal a severely high level of one
or more of the water balance factors. Scale deposits not only make pool
surfaces rough, but also reduce water circulation as scale builds up within
the filter and plumbing system.
If scale deposits are readily noticeable on pool surfaces the pH, calcium
hardness, and total alkalinity must be tested and adjusted immediately.
Most likely one factor, if not all three, is much too high and needs to be
reduced. The first step is to reduce the pH and alkalinity, since reducing
the calcium hardness level is more difficult.
If high hardness is the cause of the scale, it is best to drain a portion of the
pool water (or all of the water in a spa) and replace with fresh make-up
water that is low in hardness and total dissolved solids.
CONFIRMATION Crusty deposits on pool surfaces.
CAUSES 1. High calcium hardness.
2. High pH & alkalinity.
TREATMENT 1. Adjust pH and alkalinity to ideal ranges
(7.2 - 7.6 & 80 - 120 respectively).
2. Replace a volume of pool water with water low in hardness.
Consult a pool professional to determine the replacement
amount.
3. Use a sequestering agent to prevent scale buildup if high
hardness levels are a continuing problem.
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