Apex Alk testing drifting fast and far

[Ziggy17]

my apex is about 3 years old. I calibrate it with the Neptune solution every time I buy new reagents and often in between. I recently did the DIY maintenance kit, new pump head, tubes and cuvett. Recalibrated it and the ALK was matching my Hanna checker to about a .1 variance. I use the Hanna testers as the gold standard and an ICP as the platinum standard. In less than 3 weeks, the apex alk reading has drifted slowly but surely and now the delta between the Hannah and Apex is about .5 DKH, apex being on the high side of the two tests. Is this normal for others as well? I don’t remember it drifting quite as fast in previous years.

How often is everyone else recalibrating and what are you using to calibrate ALK? Tbh, I’m not as concerned if the calcium and mag drift and I keep the cal at 420 and the mag is a trivial 1380, so even if the calcium drifts up or down I know I’m still in a pretty good zone. I just did a test and this is what I got, however my Hanna ALK read 8.2.

 

[14 foot reef]

Remember your Hanna Alk tester is hobby grade also. It's reagents can read differently. Also there is a 5% data error stated by Hanna.
I'd say your splitting hairs, but, it is good to keep a close eye like you are.
Keep up the good work and dedication to keeping up with your water quality for your animals.

 

[Ziggy17]

Remember your Hanna Alk tester is hobby grade also. It's reagents can read differently. Also there is a 5% data error stated by Hanna.
I'd say your splitting hairs, but, it is good to keep a close eye like you are.
Keep up the good work and dedication to keeping up with your water quality for your animals.

I would agree with you, and for sure, anything affordable is hobby grade. The Hanna does seem to keep in line with my ICp tests moreso than the apex, so it’s the best of the affordable and convenient I guess. It just sucks that the apex can’t stay accurate enough to trust as a sole tester, and ALK is one of those critical 3. I’m just wondering if this is my apex issue or most of us have the same drifting issue.

 

[Waters]

I only calibrate when using new reagents......it stays pretty consistent until I get near the end of the bottle. Every once in a while I do get a strange reading but at that point I test with another method to confirm....it usually corrects itself the next time the trident tests ALK. ALK seems to be the only test out of the three that I can rely on.