If you’re serious about pool care, test strips are not enough. They’re fine for a quick chlorine glance, but they’re inaccurate at the edges of the measurement range, hard to read in changing daylight, and worthless for the fine-grained adjustments that keep a salt cell happy or prevent calcium hardness drift. A liquid drop test kit is the right tool. Here’s how to pick one.
The two reagent systems that matter
Almost all pro-grade kits use one of two chlorine measurement methods:
- DPD (N,N-diethyl-p-phenylenediamine): A colorimetric reagent that turns pink in the presence of free chlorine. Easy to read by color match. Accurate up to about 5 ppm. Above that, it “bleaches out” and gives false zeros.
- FAS-DPD: A titration method where you add drops until the color changes. Each drop equals a known concentration. Accurate from 0.2 ppm up to 50+ ppm. The pro’s choice for any pool that’s been shocked or runs higher chlorine levels.
For pools at normal residential chlorine levels (1–5 ppm), either works. For salt pools, after-shock readings, or commercial pools, FAS-DPD is the right call.
What else should the kit measure?
At minimum: free chlorine, total chlorine (difference = chloramines), pH, total alkalinity, calcium hardness, and cyanuric acid (stabilizer). Add salt if you have a salt chlorine generator. A “complete” or “K-2005/K-2006” style kit covers everything; a basic 2-way (chlorine + pH only) leaves you guessing about most of the chemistry.
Our three picks for residential pools
Taylor K-2005 Complete (DPD)
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Taylor K-2006 Complete (FAS-DPD)
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Taylor K-2005 Salt Complete
Shop NowHow long do reagents last?
Most pool test reagents are stamped with a 1-year shelf life from opening, though stored cool and dark they often work accurately for 2 years. The biggest indicator of expired reagent is reading dropping out of range (chlorine reading zero when you know it’s not, pH reading high when you know it’s neutral). Replace the reagent set, not the whole kit.
Test kit vs. digital photometer
Digital photometers (like the LaMotte WaterLink or Hanna HI 96701) automate the color-match step using a photodiode. Faster, easier to read, no eye-strain for color comparison. Downsides: $400–$1,500 cost, plus they still use chemical reagents. For most residential owners, a Taylor K-2005 or K-2006 is the right tool. Step up to a photometer if you run a commercial pool or maintain multiple pools.
Not sure which kit fits your pool? Send PST Pool Supplies your sanitizer type (chlorine, salt, bromine), pool gallons, and whether the pool is residential or commercial — we’ll match the right kit on the first try.