Hannah Checker - Low Reading Leading to Alk Overdose

[prcardinal91]

So I run my SPS dominant reef at 8.5 alk. I was testing daily with a Hannah but it's been stable so I have started to test less frequently. Dosing 145 ml alk and cal on a 150g daily. 2 weeks went by and I ran a test on alk and got a reading of 6.7. Whoa. Ran a few more Hannah tests and got the same resultsg. With 2 clams and a bunch of sps I figured this could be possible. So I started bringing it back up to 8.5 over the course of a few days. When I tested yesterday it was only at 7.5. With the brs calculator, I knew this could not be right. So I opened up a new reagent ran a few Hannah tests and ran a few Salifert tests. All came back right around 10.4.

It appears that the Hannah reagent that was open for about a month was giving me a low reading. Has anyone else had this issue with reagent going bad after a month? I am going to let the alk come back down slowly over the next few days and hope there was not too much stress caused.

 

[xabo]

There has been discussion on this: https://www.reef2reef.com/threads/i...-for-hanna-marine-alkalinity-checkers.893762/

 

[prcardinal91]

Thank you

 

[mdb_talon]

I never mind a new thread that lets people know how bad hanna alk reagent is!

 

[hllb]

The only time I've had this happen is when I had a leaky bottle. If the bottle leaks, that likely means the reagent isn't going to be good (though it takes a while to happen so you won't notice it right away). I've only had leaky bottles when 1) I removed the white disk from the cap that acts like a gasket or 2) I didn't remove all of the foil seal from the rim of the bottle, which makes the gasket not seal properly.

There could be a bad batch of reagent, though I've never had that happen. Best practices, however, is don't change what you're doing based on one test. I always keep a Salifert alkalinity test on hand and if I get a reading I don't expect I cross check it with Salifert. Most of the time they are very close and in that instance, I would dose accordingly. The one time I had a bad bottle though, they were off by about 2 dkh so I was very glad I caught that. I opened a new reagent and the Hanna was then in line with Salifert.

 

[prcardinal91]

Definitely a leaky bottle. Tank is about 5 months old from a transfer. Alk consumption has been increasing slightly over time with the new additions of coral, clams and coraline. Keeping my open reagent in the fridge now. Salifert and red sea have always been on backup

 

[James Tucker]

I had this happen to me as well as I got past the 1/2 way point in the reagent, the tests got less reliable.

 

[ReeferLou]

I am keeping my new reagent in the fridge now to see if I can avoid the low readings as the bottle empties. That was the recommendation from the other thread. I did a side by side test new vs old and difference was 1.5 dkh