Alk Calibration Fluid

[BlueWorldJeff]

Does Hanna offer calibration fluid, so I know my Alk checker is reading accurately. And if so, and the reading is off, how to calibrate?

I'm using the HI 755 ppm Alk checker with the HI 755S reagent

 

[Spdjnky]

https://www.bulkreefsupply.com/hi75...rds-for-hi755-hanna-checker-marine-water.html

 

[BlueWorldJeff]

Good stuff, thanks. I'm assuming it tests at a certain dkh. But if my checker says otherwise, can I adjust the device or just take the variance into account moving forward?

 

[Spdjnky]

Here is the response I got to my questions hope it helps. MY ? was:
Question: Hello I have the772 model
You say acceptable results are 90-110 ppm thats 1 dKH right? So what is the actual reading that you should get? My test showed 6 dKH I guess I am to convert it to ppm (nothing in instructions) that's 107.16 ppm. Which is just in the range of 90-110 you give in the instructions. This is where I'm lost because of the big swing does that mean 100 ppm would be the best?
Good morning,

Thank you for your enquiry.
The HI-755-11 CAL Check standards are designed for the HI-755 marine alkalinity Checker, as this meter measures in ppm.
There is a CAL Check standard kit that is designed specifically for the HI-772, which is the HI-772-If you would like to continue to use the HI-755-11, there is a conversion factor that can be used between the two, which is as follows:
To convert from ppm to dKH alkalinity, multiply the result by 0.056
To convert from dKH to ppm alkalinity, divide the result by 0.056
The tolerance range given of 90-110ppm is due to the accuracy on both the standard itself and the Checker. Both the standard and Checker have an accuracy of ±5ppm, so this results in a total accuracy of ±10ppm, hence the 90-110ppm range.
Any reading within this range is an acceptable reading, indicating that the meter is reading within its accuracy tolerance.
I hope this helps, but please let us know if you need any further information.
Then I asked another ?
Thank You Abi,
If I use the HI-755-11 that I have and I just used it again and got a 5.8 and 5.9 dKH readings but have to hold the top down because your test tubes won’t close all the way will this affect the reading? If it does not affect it and as you say the tolerance is what it is that to me means I should be able to use this to adjust the readings I get on my aquarium water so I know the true reading right? To me what I am asking is that if my hana checker is reading 5.8 dKH or 103.571 ppm and my aquarium water tests at 6.9 dKH how much is that reading off and what do I add or subtract to get what it really is? Can you help me understand so I can trust the actual reading I am getting because the Alk I measure always is on the low side I think.
Phil
They replied:
Good afternoon,
The HI-755-11 cuvettes are exactly the same size/shape as the HI-772-11 cuvettes, so these should fit in the Checker with the lid down no problem.
The CAL Check standards are usually supplied with a bit of sponge at the bottom of the cuvette which can stay stuck to the cuvette and sometimes prevent the lid from being stuck down so we would recommend checking this just in case this is causing an issue.
It is possible that light would be getting in from outside if the lid is not closed, but from the reading given below, it doesn’t sound like this is having any impact on the reading.
The tolerance level doesn’t give you an amount to add or subtract to your readings – the readings are what they are. The CAL Check standards will just tell you whether the meter is reading accurately or not, but from the reading given below, the meter is reading accuratelyIf it is reading accurately in the standards then we would expect it to be reading your samples accurately as well.
I hope this helps, but please let us know if you need any further information.
Kind regards,
Abi

 

[Jamie7907]

I have tested several Hanna Alkalinity checkers against a Hach titration tester and the Hanna units consistently show .6 - .7 dkh higher than what the actual Alkalinity is. For Hanna you need to differentiate between accuracy and precision. While the Hanna may not be very accurate they are very precise. In other words when your Hanna shows 7 dkh it’s more likely 6.5dkh so it’s not very accurate, however it will show the same results ( 6.5dkh) repeatedly. For what it’s worth every Hanna I’ve tested both ppm and dkh style have read higher than what the actual dkh is but without testing your checker I can’t say if yours is even off because each unit is different. If it were me I would try to hit 8 dkh on the checker which ime is more likely 7.25dkh and as long as the tank looks happy keep it there as the Hanna’s are very precise. Hth

 

[Spdjnky]

Thx for your input. I didn't start this thread but my problems are that just starting out in trying to get things right so I can have a healthy reef. My Alk readings are always low 7.8 dKH so I wanted to make sure it was not the Hana tester and according to them it's good but they have a +/- 1 dKH range that is in the tolerance level.

 

[BlueWorldJeff]

I have tested several Hanna Alkalinity checkers against a Hach titration tester and the Hanna units consistently show .6 - .7 dkh higher than what the actual Alkalinity is. For Hanna you need to differentiate between accuracy and precision. While the Hanna may not be very accurate they are very precise. In other words when your Hanna shows 7 dkh it’s more likely 6.5dkh so it’s not very accurate, however it will show the same results ( 6.5dkh) repeatedly. For what it’s worth every Hanna I’ve tested both ppm and dkh style have read higher than what the actual dkh is but without testing your checker I can’t say if yours is even off because each unit is different. If it were me I would try to hit 8 dkh on the checker which ime is more likely 7.25dkh and as long as the tank looks happy keep it there as the Hanna’s are very precise. Hth

Does this mean that the calibration fluid, if supposed to test at 8, will test at 8, but really be 7.5 dkh? If what your are saying is happening with my ALK ppm checker then I believe mine is accurately testing. I had a salifert test that I used the calibration fluid with to be accurate and salifert tested about .5 lower than Hanna but tested the value of the salifert calibration fluid accurately.

If this is the case, I'll take the variance and aim for 8.5 with the Hanna, being low 8s, high 7s in reality

 

[Spdjnky]

Can't help you out there as I don't know and will be starting this week to bring my Alk up to 9 dKH slowly and from what I can understand if I keep it in the middle I won't have to worry about that .5 dKH