Hanna dKH Checker / Calibration Check Set / Trust it or Not ???

[GoVols]

First Off:
I bought my third dKH checker during the 10% sale at MD, and it's solid as a rock.

My first dKH checker lasted about three years and came within .2 dKH to Salifert and later on with my Alkatronic.
Got water inside that unit and it was toast.

So, bought another a few months back and it read about .7 low to the old checker.

Looked into the calibration set for another $20, but it is certified at 5.0 dKH

We are taught to calibrate our refractometers with .35 solution, so that it is calibrated very close to what we mix to, and have personlly been bit by zeroing out my meter over a 3 month period of time with RO/DI.

With this in mind:
1) Should we trust a check calibration set certified, at 5.0 dKH?

2) Should there be an option to buy a set that is certified at.. say at 8.0 dKH

Thank you, GoVols

 

[Angelwolf21203]

I have hanna checkers, too. No problems with my dKH o e, but my PO4 ULR is off, according to the control set that I got. I have to call them tomorrow and discuss getting it replaced.

 

[tehmadreefer]

First Off:
I bought my third dKH checker during the 10% sale at MD, and it's solid as a rock.

My first dKH checker lasted about three years and came within .2 dKH to Salifert and later on with my Alkatronic.
Got water inside that unit and it was toast.

So, bought another a few months back and it read about .7 low to the old checker.

Looked into the calibration set for another $20, but it is certified at 5.0 dKH

We are taught to calibrate our refractometers with .35 solution, so that it is calibrated very close to what we mix to, and have personlly been bit by zeroing out my meter over a 3 month period of time with RO/DI.

With this in mind:
1) Should we trust a check calibration set certified, at 5.0 dKH?

2) Should there be an option to buy a set that is certified at.. say at 8.0 dKH

Thank you, GoVols

Why would it matter if it’s calibrated to 8 or 5 or 2 or 15? If it’s calibrated, it’s just that. All that matters is if it should read “x” using the calibration set and it does.

 

[GoVols]

Why would it matter if it’s calibrated to 8 or 5 or 2 or 15? If it’s calibrated, it’s just that. All that matters is if it should read “x” using the calibration set and it does.

Okay you trust the check set to remain at 5.0

I'm not so sure becuase it would seem better to have a set at 8.0

But I sure maybe wrong, in thinking like a refractomter's calibration / to a beam of light judging color.

 

[Dr. Jim]

I don't think that the point where it is calibrated is much of a factor. The problem with the Reference Standard is that the degree of error is plus or minus 10ppm for a 98 ppm standard! That's about a 10% range.....equivalent to about 0.1dKH. A range this great makes this reference standard worthless IMO.

 

[tehmadreefer]

Okay you trust the check set to remain at 5.0

I'm not so sure becuase it would seem better to have a set at 8.0

But I sure maybe wrong, in thinking like a refractomter's calibration / to a beam of light judging color.

Well I would hope so, lol

But ya never know as we are putting our trust in Hannah

 

[kevin_e]

You don't really calibrate it. You can't. You are using a known solution to verify. If you get, say 4.8, using a 5.0 solution, then you will manually adjust your readings going forward. i.e. you now the unit is reading 0.2 units low.

 

[Nhjmc]

I just got that checker as well I love it.

 

[GoVols]

You don't really calibrate it. You can't. You are using a known solution to verify. If you get, say 4.8, using a 5.0 solution, then you will manually adjust your readings going forward. i.e. you now the unit is reading 0.2 units low.

That is correct you cannot use it to calibrate a Hanna alk checker

If it's .2 low at 5.0 is it still .2 low at 10.0 dKH?

 

[kevin_e]

That is correct you cannot use it to calibrate a Hanna alk checker

If it's .2 low at 5.0 is it still .2 low at 10.0 dKH?

Not sure. But it seems like it is the assumption we have to make.

 

[GoVols]

@Hanna Instruments

With a light beam shooting through a colored vial:

Is a 5.0 calibration check test / more accurate at 5.0...

...than having a tester check test at a higher dKH / colored vial?

Thank you

 

[Phil D.]

With a Calibration Standard stating it's 5.0 Dkh and it reads 5.0, then you meter is accurate. As stated above, if it reads X.XX high or low, then you need to adjust accordingly. Add or subtract from the reading you get.

 

[madweazl]

I don't think that the point where it is calibrated is much of a factor. The problem with the Reference Standard is that the degree of error is plus or minus 10ppm for a 98 ppm standard! That's about a 10% range.....equivalent to about 0.1dKH. A range this great makes this reference standard worthless IMO.

In what situation would .1 dKh make a difference? I sure cant think of any.

 

[GoVols]

With a Calibration Standard stating it's 5.0 Dkh and it reads 5.0, then you meter is accurate. As stated above, if it reads X.XX high or low, then you need to adjust accordingly. Add or subtract from the reading you get.

If the offset at 5.0 is .2, do we or you have proof, that that offset is the same at 10.0?

I don't know the awswer, but would be open to an expert in that area, with the proof to back it up.

If there is no difference in going with a 8.0 colored vail, it would sure make me feel more confident on spending $20, in case I get another, brand new bad Hanna checker.

 

[Phil D.]

As an Electronics Tech, the offset would be the same as the sensor would have the same tolerance errors at either range.

 

[GoVols]

As an Electronics Tech, the offset would be the same as the sensor would have the same tolerance errors at either range.

Thank you

 

[Phil D.]

Welcome!! Anytime!

 

[Dr. Jim]

In what situation would .1 dKh make a difference? I sure cant think of any.

Oh...actually it is much more than 0.1kKH. (I did the calculation a long time ago and was thinking it was 0.1 only....sorry).

The Hanna Standard is 98ppm +/- 10ppm (which is +/- 10%)
So, if my math is correct......If your checker matches the standard exactly, it could actually be off by 10% in either direction. So, if you measure your tank water at 8.0, it could actually be any where between 7.2 and 8.8. That's quite a difference!

 

[Randy Holmes-Farley]

I hope folks realize that this sort of "calibration" does not by any stretch of the imagination demonstrate that you get accurate readings from the Hanna. It should be called a color standard for checking the electronics, not an alkalinity standard, which would require adding reagents to it and using the normal alk check procedure.

 

[Randy Holmes-Farley]

As an Electronics Tech, the offset would be the same as the sensor would have the same tolerance errors at either range.

Can you clarify?

The standard is an absorbance standard.

I don't see how you can know where the actual error is in the measurement, and so cannot know how it relates to mismeasurement at different absorbances.

If it is just an offset in absolute absorbance, it will read off by that amount at any absorbance.

If it is a slope offset, then the size of the error will propagate with the absorbance itself.

The true result might be anything in between (or something else entirely).

That is why folks doing calibration of any absorbance technique use multiple points bracketing the value, not just a single point.