"old" reagents ... Specifically hanna alk solution

[BryanM]

Old is in quotes because its not even a year old.

But basically its been testing 10.5, 10.7, 11, and I've been backing OFF my dosing to get this lower, and I just didn't believe it.

I had corals delivered by a local vendor and they nicely tested my alk - 9.0.

I get new reagent, 8.5.

I now have a salifert as a backup when numbers don't seem to make sense, but this testing error that I do not think is my fault is super frustrating.

(Hanna marine master tester, all vials rinsed with rodi and stored with rodi in them).

 

[Reefer Matt]

I don’t have the Marine Master kit, but I do swirl (not shake) the alk reagent a few times before use. My belief is that it doesn’t stay homogenous in storage, and just make it a habit with most liquids before use. There are times when the reagent may simply be faulty too. If in date, Hanna will send you a new one for free if it is.

 

[Reginald Reefer III]

I often run into the HR Nitrate powder being wildly off. One packet reads 0 and the next reads perfect. One reads off the charts and the next reads way too low. PO4 doesn't seem to have that issue.

Might also be scratches/blemishes in the cuvettes causing reading problems.

 

[Randy Holmes-Farley Verified Community Expert]

I often run into the HR Nitrate powder being wildly off. One packet reads 0 and the next reads perfect. One reads off the charts and the next reads way too low. PO4 doesn't seem to have that issue.

Might also be scratches/blemishes in the cuvettes causing reading problems.

I use the HR nitrate and have not noticed issues, but then again, I’ve not really tested it against standards. I also keep the reagents in a mini fridge.

 

[Dr4gula.f32]

My hannah alk is all over the place as well. So bad I sent it back to Hannah to check it out. They swear its fine and send it back. I can test the same water 3 differernt times and have a 1dkh delta of readings

 

[BryanM]

I use the HR nitrate and have not noticed issues, but then again, I’ve not really tested it against standards. I also keep the reagents in a mini fridge.

Why a fridge, did I miss that as a requirement?

 

[Dr4gula.f32]

Why a fridge, did I miss that as a requirement?

Hannah told me that the reagents last longer when stored in the fridge.

 

[Randy Holmes-Farley Verified Community Expert]

I don’t know if it matters, but most degradation reactions of organic molecules, such as the colored dyes, are slowed at lower temperatures and accelerated by heat.

 

[John Bolden]

I have my hanna alk tester and it is always all over the place aswell as my cal tester which I think is cause my powder is expired by 2 years lol. i have tried everything but my alk is always 2 dkhunder what the LFS tests is and always varies .2-.3 even with the same exact tests.

 

[Randy Holmes-Farley Verified Community Expert]

I have my hanna alk tester and it is always all over the place aswell as my cal tester which I think is cause my powder is expired by 2 years lol. i have tried everything but my alk is always 2 dkhunder what the LFS tests is and always varies .2-.3 even with the same exact tests.

FWIW, I don’t think a 0.2-0.3 dKH variation is unexpected or a problem. The 2 dKH offset from the lfs is a concern, but you cannot tell which is more accurate from that info.

 

[John Bolden]

I have my hanna alk tester and it is always all over the place aswell as my cal tester which I think is cause my powder is expired by 2 years lol. i have tried everything but my alk is always 2 dkhunder what the LFS tests is and always varies .2-.3 even with the same exact tests.

FWIW, I don’t think a 0.2-0.3 dKH variation is unexpected or a problem. The 2 dKH offset from the lfs is a concern, but you cannot tell which is more accurate from that info.

I believe they use an aqua spin photometer and less and less I trust it. Sunday I tested with my Hanna tester and got 6.6 alk then added 5ml of esv alk then waited 45 minutes. I took my water sample took it to the lfs they said my alkalinity was 8.1 then I did a water change and tested again and got 7.5 from my Hanna tester. So either 1 their tester is wrong 2 the alkalinity in their water is super low (I buy salt water from them) or 3 my Hanna tester is consistently low. The previous week they gave me the results and told me the alk was off and it was really 7.9 not 6.8. Have you seen where a Hanna egg has needed recalibrated?

 

[Randy Holmes-Farley Verified Community Expert]

I’ve not seen an example where anyone got the Hanna colored calibration fluids and found they were off. Most issues relate to other aspects of them, such as the vials, reagents or procedures.