When Cynthia Wilson noticed a persistent leak in a commercial heater she’d been servicing, she did what any pool service technician would do — called the manufacturer to request fulfillment of the warranty. But when the manufacturer’s investigator performed a water analysis, the results caught Wilson off-guard.
“Their evaluation worksheet said that we’d failed to
maintain the necessary [calcium hardness] levels for the equipment
warranty to cover the damage,” said the vice president of
operations at Like New Pool Services Inc. in San Diego.
“Even though our water was balanced according to the
Langelier Saturation Index, it was considered corrosive by the
Ryznar Stability Index.”
This development would likely have thrown most service people for a loop.
Within the pool industry, the Langelier Index is taught almost
exclusively, and many service veterans remain unaware that any
other water balance indices even exist. “The Ryznar Index is
basically not taught by anybody, except that it’s sometimes
briefly mentioned in certified pool operator classes,” said
Alison Osinski, Ph.D., president of Aquatic Consulting Services in San Diego.
Nevertheless, several heater manufacturers have advocated or
required the use of the Ryznar Stability Index for years. Though
these manufacturers also tend to promote the Langelier Saturation
Index, some pool chemistry experts say the two indices aren’t
always compatible. “These two formulas can conflict,”
Osinski said. “They’re looking at the same issues, more
or less — but the Ryznar Index wants you to have much higher
Representatives of companies that support the Ryznar Index explain
that this higher calcium hardness mediates the water’s
potentially corrosive effects on metals. “The Ryznar Index is
oriented toward protecting equipment’s metallic surfaces,
whereas the Langelier Index is focused on protecting the calcium of
the pool shell,” said Rich Murphy, national pool sales
manager at Lochinvar, a heater manufacturer whose warranty
specifies the use of both the Ryznar and Langelier Indices.
While the Langelier Index is geared to prevent either scaling or
etching, the Ryznar Index is designed to allow a slight coating of
calcium to accumulate on metallic equipment, where it acts as a
But therein may lie the problem. “In Southern California, our
water already contains too much calcium,” Osinski said.
“That buildup causes all kinds of issues with oversaturation,
and it clogs up our pipes, and coats our heater elements, and
damages equipment.” Thus, Osinski and others have pointed
out, adding additional calcium to bring the water into
Ryznar-acceptable balance could lead to excessive calcium scaling
in some cases.
This leaves service techs like Wilson feeling caught between a rock
and a hard place. For other pool professionals concerned about a
situation like this, experts agree the safest bet is to become
familiar with the equipment’s warranty paperwork — and
if the manufacturer mentions the Ryznar Stability Index, to try to
keep the water balanced into the range where both the Langelier and
Ryznar indices will consider it to be noncorrosive.
“If you maintain a Langelier Index value of 0.0 to +0.5,
you’ll be right in the Ryznar Index’s ideal
range,” said Kim Skinner, co-owner of Pool Chlor in