The National Pool Industry Research Center has released
the results of its study of pool and spa test kits.
The research, completed in March 2007, examined 14
products from seven manufacturers and tested them against a
laboratory value and precision between multiple
Participating firms included AquaChek, Guardex/BioLab,
LaMotte, Pentair Water Pool and Spa, Jack?s Magic
Products and Palintest USA. Tests were administered by
NPIRC researchers and teams at six universities.
The two most notable trends among the test kits are the
tendencies to underestimate chlorine and overestimate
calcium hardness. On average, kits produced a chlorine
reading 30 percent lower than the laboratory test. The
average difference in calcium hardness was nearly 40
However, human error may play a role in these
?Every test company I know says
[there?s] a 10 percent variability because
it?s a field kit,? said Tom Seechuk,
industrial products marketing manager at Lamotte Co. in
The drop size can introduce another variable because the
tips of bottles can become charged, creating a small drop,
The subjective nature of colorimetric tests also could
have contributed to result variances.
?Because colorimetric tests are a matter of
interpretation, they?re certainly going to be a
problem unless you have a colorimeter,? Seechuk
said. ?But a lot of [service] companies
don?t want to spend the money.?
NPIRC was established in 2003 to research issues
affecting the aquatics industry. The group is funded
primarily by the National Plasterers Council.