"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.