Hanna Alk accuracy

[Thor2j]

I keep seeing these posts from people with Guardian KH saying their hanna Alk colorometers were off by more then 1 dkh even though their hanna test samples tested perfect. Anybody double or triple check against other reliable sources??

 

[Randy Holmes-Farley Verified Community Expert]

In this test, it gave similar results to others, such as the Salifert kit:

https://www.reef2reef.com/threads/b...i-hanna-triton-awt.234660/page-2#post-2737147

 

[Hanna Instruments]

I keep seeing these posts from people with Guardian KH saying their hanna Alk colorometers were off by more then 1 dkh even though their hanna test samples tested perfect. Anybody double or triple check against other reliable sources??

Is the pH electrode in the kH guardian properly conditioned, cleaned and calibrated?

 

[Hanna Instruments]

I keep seeing these posts from people with Guardian KH saying their hanna Alk colorometers were off by more then 1 dkh even though their hanna test samples tested perfect. Anybody double or triple check against other reliable sources??

Check out our top 10 pH electrode mistakes https://www.reef2reef.com/threads/top-10-mistakes-in-ph-measurement.315029/

 

[Thor2j]

Check out our top 10 pH electrode mistakes https://www.reef2reef.com/threads/top-10-mistakes-in-ph-measurement.315029/

Problem is they are verifying it with other test kits.

 

[JimWelsh]

I keep seeing these posts from people with Guardian KH saying their hanna Alk colorometers were off by more then 1 dkh even though their hanna test samples tested perfect. Anybody double or triple check against other reliable sources??

Do you have links to specific threads you can share?

 

[Thor2j]

Do you have links to specific threads you can share?

https://www.reef2reef.com/index.php?threads/288011/

Its throughout, but check the last page or 2. Theres a few there with guys who know what they are doing.

 

[Hanna Instruments]

https://www.reef2reef.com/index.php?threads/288011/

Its throughout, but check the last page or 2. Theres a few there with guys who know what they are doing.

Its hard to say for certain what specifically is causing the difference between the two methods of testing. We recommend using our Calibration Standards to always validate the accuracy statement of your Checker if ever concerned about your reading. The value produced from out HI772-11 will determine if your Checker is functioning properly (within the measure of uncertainty) but also will help determine if your other methods of testing are accurate or not. The HI772-11 is a high-quality set of standards manufactured in our state-of-the-art facility and comes supplied with a Certificate of Analysis. The Certificate of Analysis provides the lot number, reference values and expiration date for traceability when certifying the Checker®HC. The value produced in the standard is highly accurate, as being produced under strict quality control. It is possible for Checkers to become less accurate due to improper care, getting the light source wet or just simple malfunction. I could not find anything specifically about whether or not the pH electrode for the Kh guardian was cared for properly in this thread. In general, when working with pH electrodes, its best practices to calibrate before each use to be certain of accuracy. However this is not realistic for most hobbyists, but its important to note that pH electrodes will only function properly if they are cared for correctly. Any sediment, mineral deposit or calcification on the sensing glass can lead to inaccurate readings. Calibration must be done in order for proper titration to occur, as the end point value might not be true and one could over/under titrate the sample, leading to inaccurate results. We use pH electrodes in many of our automatic titration systems and determining the slope/offset of that electrode is usually the first troubleshooting tip to determine if it is functioning correctly.

If they are verifying it with other test kits then it could a malfunction in the Checker or could be problems with the other test kit they are validating it with. There are a lot of threads that compare our Checker to other test kits and many of them are very close in results. Its important to make sure all reagents are stored in the correct temperature, humidity level and any other guidelines outlined by the manufacturer. All of our reagents have MSDS sheets where you can look up proper storage/handling instructions.The HI755-26/Hi772-26 Marine Alkalinity Reagent follows the Colorimetric Method in which the reaction causes a distinctive range of colors from yellow to green to blue to develop. When keeping this reagent you need to store at room temperature (+15°C to +25°C) (59F-77F) and protect from light and moisture. Do not keep them in your stand cabinet or refrigerator.

 

[JimWelsh]

I could not find anything specifically about whether or not the pH electrode for the Kh guardian was cared for properly in this thread.

FWIW, the KH Guardian manual says, "We recommend exchange the pH probe every three months, and perform pH4 and pH7 calibration every time at the exchange." There is a video that has been posted online of the KH Guardian in operation that shows that in between tests, the probe is stored in tank water.

 

[Hanna Instruments]

FWIW, the KH Guardian manual says, "We recommend exchange the pH probe every three months, and perform pH4 and pH7 calibration every time at the exchange." There is a video that has been posted online of the KH Guardian in operation that shows that in between tests, the probe is stored in tank water.

Do you know if that three month mark ever changes? What if someone measures alkalinity 20 times per day versus 1 time per day on their kH guardian? Storing a pH electrode in saltwater is not the most ideal condition, however it is better than say freshwater or de-ionized water. Aquariums are not the harshest of applications but that is still dependent on the type of aquarium. A pH electrode in saltwater aquarium will last longer than an aquarium with very low conductivity water. The main reason is that the solution inside the reference cell of the probe is very salty, so when the probe is placed in saltwater the diffusion of the reference electrolyte will be less than when it is placed in very low conductivity water. The amount of diffusion and any osmotic effects are factors that will cause a probe to fail over time. In process applications it is common for an industrial user to leave the probe constantly in the solution. The pH values are verified by having a portable meter that is used to check the accuracy of the process reading. The controller is adjusted to match the portable (process calibration). The process probe is pulled periodically for a traditional calibration and that will depend on the process but a typical time frame would be monthly. For aquariums we work with it would be recommended to take the probe out and and check calibration weekly. If the reading is substantially different from the pH buffer then it will need to be re-calibrated. If there is not much change then the time frame can be increased. Its usually a good trouble shooting tip to submerge the pH electrode in a buffer to check the accuracy periodically, but it sounds like kH guardian has planned a conservative time frame with the exchanging of their pH probe.