FAS-DPD drops never quite hit clear, just fade out on me

Started by swamp_tyler · · 1 reply
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#1
doing my FC test with the K-2006 like always and normally i get a clean snap to clear but lately its just fading lighter and lighter and i cant pin down the exact drop it goes clear on. shaking the bottle good, sample's the right size, reagent isnt expired far as i can tell. still get a number i can work with but now im second guessing if im over or undercounting drops by a couple. anyone else run into this in the heat, does the reagent go weird above like 95 out or is my eyeballing just getting worse. pool's been steady otherwise, FC holding, just wanna trust my own numbers again

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#2
Had the same fade-out thing happen mid-July when garage was over 100 and I keep my reagents in there. Turned out the DPD drops themselves were fine, problem was my eyes adjusting slow in bright light, that fade you're describing reads different depending on if you're testing in full sun or shade. I started doing the test in shadow every time, same spot, and the snap came back sharp. Also cracked a fresh bottle just to rule it out since mine was pushing a year old, and that helped too even though it "smelled fine." If FC's holding steady and the number you're landing on matches what your test strips or the pool's behavior suggests, trust it, but get out of direct sun for the reading.