KH Readings

[Shredded]

I have had my KH Director up and running for a couple of months. It took a week or so but we finally got it dialed in. Every reading matched my Hanna exactly, every time. At that point I turned on the controller section. It worked very well, was extremely impressed... Then a couple of weeks ago, I received a warning that my KH was out of range. (I'm set for 8.5, with a low of 8 and a high of 9) The reading was 14. So I ran home and kicked off a test and what I found was one of my heads (the water sample) had gone out. I've heard that this happens occasionally and while not what I wanted it certainly was better then my KH going from 8.4 to 14 in 4 hours. I pulled off the cover, rollers and spindle. There were pieces of the blue cover on the roller as if it had melted it off. I have one unused head on one of my controllers and I took those parts and rebuilt the head. It worked fine and not only that when I calibrated, it was the same calibration as before. I went thru the initialization procedure and then ran a test. The reading was 11. Well, I always ignore the first few readings until it gets dialed in as the first reading is always trash. And it did dial in, between 10 and 11. No matter how many times I go thru complete calibration, starting from scratch, the readings are now always in this range. My Hanna still reads in the 7 to 8 range and I have checked my multiple other brand tests. The tank looks great, corals are happy, these readings are just off. Now, I could always adjust the reading, but I know it is capable of being exactly on the money. I have recalibrated the probe (ever had a probe go bad?), all the pump heads multiple times, remeasured the sample line (that never changed but it has to be something) and it now it only measures my KH in this range. (see my graph attached. the high point and low point were immediately after a calibration) I was really stumped. Suddenly I realize that there was something different. When my head crashed, and I was recalibrating i did run out of my first bottle of reagent and i had to pop a new bottle that I had ordered online from a place I had never ordered from before. Could that be it? Weren't there originally issues with reagent. If so, are there certain lot numbers. Has this exact thing happened to anyone else?
Thanks in advance.
Jeff

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