
Originally Posted by
PoolDoc
It goes to 10, nominally. But 9 of 10 people cannot distinguish a 5 ppm FC level from a 10 ppm FC level, using that kit. Diluted, you're adding additional error, so now you can't distinguish 7 ppm from 25 ppm!
Additionally, if the FC = ~15 - 20, you'll read maybe 2 - 5 ppm. If the FC > 25 ppm, you'll read FC=0. Very *experienced* pool operators can recognize those errors . . . but then we don't deal with very experienced pool operators. Put plainly, DPD color match testing is INFERIOR in accuracy, and VERY INFERIOR in reliablity, to OTO tests.
Many of the criticisms of OTO testing seem to have originated as a sales ploy by Palintest, back in the day when the DPD test was still patented and very profitable.
Pool owners with K2005 kits need to buy (a) a cheap OTO kit (quick & bomb proof -- if not very accurate -- chlorine testing to 50 ppm) and (b) a K1515 DPD-FAS add-on (accurate FC testing to 50 ppm).
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