Wow, I had this exact situation happen to me last week! I noticed a ~0.4 decrease in dKH between reagent bottles, and thought I had stumbled across a bad batch.
After installing my new ReefBot, which was providing results that lined up with the new reagent, I realized that I had either experienced a sudden alkalinity drop, or that my previous reagent had drifted.
I now realize it was the latter! Lesson learned- dispose of the reagent well before the bottle is empty.
After installing my new ReefBot, which was providing results that lined up with the new reagent, I realized that I had either experienced a sudden alkalinity drop, or that my previous reagent had drifted.
I now realize it was the latter! Lesson learned- dispose of the reagent well before the bottle is empty.
