I have had the same problem with Hannah twice in the last 4 years. Now I will only use Salifert and the Hannah as a double check if necessary. I would never trust Hannah as my sole method of determining alk.
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so is your livestock suffering?
https://www.bulkreefsupply.com/2-pack-testing-cuvettes-caps-hanna.htmlThanks ! I didn't see those ! I figured the inserts were just for keeping out debris .
Our HI772 dKH Alkalinity Checker has an accuracy statement of ±0.3 dKH ±5% of reading. So if your Checker reads 10.0 dKH the measure of uncertainty would be ±0.5 dKH or a range from 9.5-10.5 dKHI’m struggling to find something of value in that response. Speaking for myself, I already do all of that. The issue is not the procedure, it’s the reagent. I hate to say it, but I may just have to switch to Salifert.
Our HI772 dKH Alkalinity Checker has an accuracy statement of ±0.3 dKH ±5% of reading. So if your Checker reads 10.0 dKH the measure of uncertainty would be ±0.5 dKH or a range from 9.5-10.5 dKH
The major advantage of using a colorimeter, or digital test, is you can measure accuracy without subjective human error (so long as instructions are followed). Other chemical test kit brands may claim to have an accuracy statements but you cannot quantify inaccuracies brought about by judging color changes. We regularly test our lot numbers from stock against high end lab equipment used in professional water quality analysis centers. Our Checkers/reagents always preform within, or better, than their accuracy statement.
We do not use accuracy statements for any chemical test kits, nor do most analytical chemistry brands. This is because an accuracy statement is usually reserved for instrumentation with digital displays of some sort. Human interpretation of color is subjective and thus you cannot measurably quantify what that measure of uncertainty will be due to differences in how people observe colors.
;Wideyed that's way to muchWow, +/- 0.5 dKH.
I’m struggling to find something of value in that response. Speaking for myself, I already do all of that. The issue is not the procedure, it’s the reagent. I hate to say it, but I may just have to switch to Salifert.
I have the same issues,been up my doser to fine out the check reagent is off ~1dkhI was searching R2R for something else related to alk, and came across this thread. I think the OP is on to something with respect to inconsistency between reagent lots. I just switched bottles from lot #7522 expiring in 11/2019 to a lot that expires in 2020 (I forget the lot # and am too lazy at the moment to go look). I found a difference of 0.8dKH between the lots - taking samples back-to-back in the same vials, same process, etc. I did it twice with the new lot to be sure (could not retest the old lot because the bottle is now empty).
I've never noticed such a big swing when starting a new bottle before, and I was hoping that Hanna would directly address this with either a comment about a bad set of lots, or at least to tell us that this is "normal" so that I would know to always test the new lot side by side with the old lot.
Now I'm going away for two days, and will return with a salifert test kit on Saturday to see how it compares to this new lot in the Hanna. Like others, I switched to Hanna because I liked the readout vs. trying to interpret colors, but if there is a lack of reliability on the Hanna reagents, then I may be switching back.