Hanna Alkalinity Tester

[Cczman]

Recently I have been having issues with wide swings in readings on my Hanna Alkalinity Marine Tester. Reading in ppm range from 100 one day to 185 the next day.

I've checked again the calibration fluid and readings were 75ppm on a 100ppm calibration solution one day then right on the next day.

This has happened several times over the past couple of weeks. Works fine one day, then reading errors the next. Unit is only about 1 year old and reagents are brand new.

Sent message to Hanna but no word back from them.

Anyone else having similar issues?
Any more reliable and accurate cost effect test kits out there for alkalinity?

 

[bruleyii]

Do you have any other test kits to compare it to? That would be a quick way to see if it really is your test kit causing the issue.

 

[Randy Holmes-Farley Verified Community Expert]

Most alk test kits do an OK job, and my DIY is certainly plenty accurate for reef applications (likely better than many kits):

A DIY Alkalinity Test: By Randy Holmes-Farley - REEFEDITION
https://www.reef2reef.com/blog/a-diy-alkalinity-test-by-randy-holmes-farley

 

[Mrx7899]

I use red sea alk test kilt and a alk they are usually pretty accurate few months ago when Hanna was having problems with the reagent it was said that you should store the bottle upright not on its side as it reacts with the cap and it would cause inaccurate readings. Since then I have been storing it upright and haven't had a problem

 

[Mrx7899]

I use red sea alk test kilt and hana alk they are usually pretty accurate few months ago when Hanna was having problems with the reagent it was said that you should store the bottle upright not on its side as it reacts with the cap and it would cause inaccurate readings. Since then I have been storing it upright and haven't had a problem

 

[Cczman]

I do have salifert test kit which always gives different readings than Hanna but assumed if my Hanna readings were close on the Calibration then that would be the most accurate.
I hadnt heard about storing upright. Thats surprising since the reagent comes stored on its side in the box. If its already reacted with the cap is it to late?

 

[ksfulk]

I do have salifert test kit which always gives different readings than Hanna but assumed if my Hanna readings were close on the Calibration then that would be the most accurate.
I hadnt heard about storing upright. Thats surprising since the reagent comes stored on its side in the box. If its already reacted with the cap is it to late?

There are two seperate issues here that are getting confused.

1. Hannah had a batch of reagents that were reacting with a new type of cap liner. They recalled all of those reagent lot numbers. You can go to Hannah's site and see if you have the impacted reagents. If so, fill out their form and they will send you new reagent. The new reagents do not react with the cap liner. You should always store OPENED bottles upright - thats just plain lab safety
2. The Alkalinity reagent reacts with the CO2 in the air once opened. If you are no judicious about closing the cap immediately upon use, and if you tear the entire plastic seal off of the reagent, you are more apt to have the reagent react with the atmospheric CO2 and have your ALK number "wander". You can prevent this from occuring by a small degree by only exposing the reagent to air for as long as you need to. Meaning open it up, take your sample and close the cap. Granted this doesnt matter too much if you are going through reagent every few weeks, but when people use one bottle of reagent for 8-12 months the exposure times add up.

Also, expiry on reagent bottles are only for UNOPENED bottles. Once you open them up, they have a finite lifespan.