Taylor
Taylor test kits and the R-numbered reagents that refill them: which kit measures chlorine how, and the two phenol reds you must not swap.
Test kits
- Taylor K-2005Taylor's K-2005 color-match kit: the DPD chlorine and bromine scale and where it stops, how it differs from the K-2006, and every reagent number.
- Taylor K-2006CTaylor's K-2006C drop kit: what each test measures, where its chlorine range stops, how it differs from the K-2006 and K-2005, and every reagent number.
Before you buy Taylor
Reagents have numbers, and two of them are traps
Taylor sells refills by an R-number rather than by kit, which is what makes a twenty-year-old comparator worth keeping. R-0001 and R-0002 are DPD 1 and 2, R-0003 is DPD 3 for total chlorine, R-0007 is thiosulfate, R-0009 sulfuric acid, R-0013 cyanuric acid. A letter after the number is the bottle size.
The trap is phenol red. R-0004 and R-0014 are both phenol red and are not interchangeable — different concentrations for different comparator blocks, with different test cell volumes behind them. 2000 Series comparators take R-0004; Residential comparators take R-0014. Order by the number in your kit's instructions, not by the words on the label.
Every reagent and strip carries a best-by date and a lot number, and Taylor's position is to replace the item once it is past the best-by. Storage is 36°F to 85°F, out of direct sunlight and away from pool chemicals. Taylor also says to replace the comparator itself every two to three years — residue builds up inside the cell — and to clean it with a couple of drops of R-0009 and a bristle brush.
K-2005 or K-2006 is a question about one test
Taylor's own answer is blunt: the only difference between the two kits is the method used for testing chlorine. The K-2005 matches color against DPD standards; the K-2006 titrates with FAS-DPD, one drop at a time. pH, alkalinity, hardness and cyanuric acid are the same tests in both.
That one difference decides resolution. Color matching reads against fixed standards and stops where the standards stop. FAS-DPD counts drops, so it resolves 0.2 ppm per drop on a 25 mL sample and keeps going to 20 ppm, which is why it is the kit people reach for when shocking or chasing combined chlorine.
A letter suffix on the kit is bottle size, and it buys test count rather than capability: a K-2005 gives about 110 free chlorine tests, a K-2005C about 300. Taylor's stated accuracy is half the distance between two color standards for color matching and plus or minus one drop for drop tests.
One interference is worth knowing before blaming the kit. Monopersulfate, the active in non-chlorine shock, reacts with R-0003 and produces false total and combined chlorine readings. Taylor sells the K-1520 interference remover, or reagent packs K-2041 and K-2042 for an existing kit.