75pxatr
Community Member
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.
Hannah Alkalinity Refill inaccurate.
- Thread starter Terry Brown
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Justfebreezeit
Valuable Member
My new bottle that tested 1 dkh lower out of the gate seems to be consistent to itself at least. Getting normal the normal drop between dosing. Honestly this is fine for me. I hate titration.
steveaus10
Community Member
so is your livestock suffering?
Mine have, yes. I've been running in mid 7's (Hanna) and recently allowed it to increase to just above 8 dkh since I figured this was a safer range and closer to what many acro tanks run. My acros did not like it and I subsequently dropped it back down. My test today was 7.784 Hanna, 8.6 Salifert. I would imagine when I was up around 8.2 Hanna, I was probably in reality above 9 dkh. Our tanks are all about consistency, but trying to maintain consistency with a test kit that is 1 dkh off is a very tricky proposition.
Hanna Instruments
Active Member
https://www.bulkreefsupply.com/2-pack-testing-cuvettes-caps-hanna.html
We sell two cuvettes and 2 caps for $8.00
Hanna Instruments
Active Member
Always rinse your cuvettes with RODI water after each test and with saltwater sample before a new test is preformed to prevent unintended dilution of sample.
•The alkalinity reagent is very pH sensitive and any saltwater or outside contaminants can alter the pH of the reagent causing inaccurate results. Make sure no saltwater or other contaminants enter your reagent bottle and if questionable results are obtained open a fresh reagent and preform multiple tests to confirm results.
•Always use the new syringe and tip provided with each new reagent. Do not use the old syringes/tips for new reagent bottles.
•Using a syringe with dried or crusty reagent on its tip is not ideal and syringes should be cleaned with RODI water periodically to prevent corrosion.
•The alkalinity reagent is very pH sensitive and any saltwater or outside contaminants can alter the pH of the reagent causing inaccurate results. Make sure no saltwater or other contaminants enter your reagent bottle and if questionable results are obtained open a fresh reagent and preform multiple tests to confirm results.
•Always use the new syringe and tip provided with each new reagent. Do not use the old syringes/tips for new reagent bottles.
•Using a syringe with dried or crusty reagent on its tip is not ideal and syringes should be cleaned with RODI water periodically to prevent corrosion.
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.
Hanna Instruments
Active Member
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.
Wow, +/- 0.5 dKH.
Danj
Community Member
Thanks Hanna, appreciate you weighing in on the discussion and I definitely agree, digital displays have significant advantages over subjective color comparisons. I do have a question regarding the specs, is there a published repeatability rating of the device? I think this would go a long way towards aligning with the mantra that you see in our hobby, vaguely summarized as "I don't care too much about absolute numbers as long as they're stable."
(Image provided just to nip any terminology confusion in the bud, since I know there's often a lot of confusion about what accuracy, precision, and repeatability mean in a scientific context)
If the gauge repeatibilty is low, then I think it has a tendency to send many of us into a mad scientist loop where we're correcting for perceived fluctuations that don't exist.
The impression I'm getting is that we can expect individual batches to be highly repeatable test-to-test within the batch but with the specified accuracy offset you've stated. Basically the leftmost target in my image. Then when a new batch is introduced, it would have a roughly equally tight grouping with a new offset as dictated by the accuracy spec. Would you say I have that summarized fairly?
(Image provided just to nip any terminology confusion in the bud, since I know there's often a lot of confusion about what accuracy, precision, and repeatability mean in a scientific context)
If the gauge repeatibilty is low, then I think it has a tendency to send many of us into a mad scientist loop where we're correcting for perceived fluctuations that don't exist.
The impression I'm getting is that we can expect individual batches to be highly repeatable test-to-test within the batch but with the specified accuracy offset you've stated. Basically the leftmost target in my image. Then when a new batch is introduced, it would have a roughly equally tight grouping with a new offset as dictated by the accuracy spec. Would you say I have that summarized fairly?
crawling junk
Active Member
;Wideyed that's way to much
OP
OP
Terry Brown
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DivingTheWorld, I agree with you. I am very through with my testing procedures. And all I heard Hanna saying is their detectors are accurate. Their statements do not address the consistency of the Reagent.
I have many thousands of dollars invested in Corals and fish. Hannah checkers being 1 DKH off, as many people have stated in this thread, is not acceptable.
I am going to have to go back to the Salifert.
I 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.
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.
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zoasaholic
Well-Known Member
I have the same issues,been up my doser to fine out the check reagent is off ~1dkh
Going back to salifert
Joe Batt
Active Member
I also notice a difference between batches of reagents. All I do is do the last test with an old reagent followed by the first test with a new reagent. I get an offset that then becomes the baseline for the new bottle. I am more concerned with consistency test to test within a bottle than the difference one to the next.
DaveRaz
Active Member
We went through this a couple years ago and they changed the cap seal from foil to plastic. All was fine until until here recently. I put the checker in the drawer and started using salifert a few weeks ago. The checker is still in the drawer.
OP
OP
Terry Brown
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Hanna Instruments any feedback on whats causing the issue of inconsistent reagents?
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