Be sure to check the dates on the liquid chlorine/bleach- it degrades over time & depending upon how it was stored (outside in the hot sun etc.)
Fresh stuff should yield roughly the results of
PoolMath based on it’s percentage.
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The frog’s chlorine itself isn’t necessarily the issue- if you can gauge its rate of dispersment, it’s the “minerals” & other “proprietary” ingredients that make folks chase their tail because they effect multiple parameters in unknown quantities. I agree that usually most people tend to have underchlorinated tubs with that system- also the dichlor/ then bleach method &
FC/CYA Levelsstill apply. You could make use of your current chlorine cartridge if you wish whilst having some cya in the water the higher fc it was giving you shouldn’t be irritating.
The method’s name should really be changed to the “reach 30ppm cya then use some form unstabilized chlorine method”.