KH Reference Solution - how to use?

[VJV]

Hi, understand this maybe obvious for a lot of people but if anyone can let me know how they use the reference solution to test the kid as well as your regular test kits (such as Hanna All Checker) I would be most grateful.

KHD: my guess is that I will add the number of ml required to perform a kh test to a separate graduated container, drop the sample water tube inlet into that container and perform the measurement? Follow up questions: would it be required to completely flush the measurement cell prior to doing such a test in order to avoid contamination from residual tank water?

Hanna Checker: I have tried setting the baseline with RO and than fill the cylinder with the reference solution but the result came out zero. I than filled the cilinder with the reference solution, zeroed the checker, added the checker reagent to the ref solution, tested again but the result came out at 5,7dKh...? I am sure I must have done something wrong here..

Many thanks and kind regards.

 

[Vinny@GHLUSA]

Use the reference fluid like you would with any water sample.
The only difference here is you have to empty the KHD measurement cell and flush with the reference fluid so it does not get cross-contaminated with your tank water.

1. Run Empty cell function on KHD
2. Pour enough fluid for flush and actual test into a separate cup
3. Run flush function
4. Do 2-3 tests using reference fluid

After you get the results, empty the cell again, then flush with your tank water.

 

[VJV]

Use the reference fluid like you would with any water sample.
The only difference here is you have to empty the KHD measurement cell and flush with the reference fluid so it does not get cross-contaminated with your tank water.

1. Run Empty cell function on KHD
2. Pour enough fluid for flush and actual test into a separate cup
3. Run flush function
4. Do 2-3 tests using reference fluid

After you get the results, empty the cell again, then flush with your tank water.

Thanks Vinny. I did not empty nor flush but have performed two tests already (3rd is undergoing) and the first test came out at 7,1dKh, the second test at 6,6dKh and the third at 6,5dKh.

I guess the first test was cross contaminated with the tank water and why it read higher than the second and third...?

In any event, this means that my KH Director is about 1dKh off, which coincides with the readings I was getting from my Hanna Checker as they have been consistently 1dKh higher than the KHD.

Any suggestions would be much appreciated.

 

[Vinny@GHLUSA]

Yes, the varying results is the outcome of a cross contaminated sample.

Trust the readings from the KHD as it will give you more repeatable results than the checker and is not susceptible to the common factors which alter the end-result of this kind of test kit. If you are more comfortable seeing the results from a conventional kit vs. a lab grade instrument, you can use the KHD adjustment tool to get the numbers to match.

 

[VJV]

Yes, the varying results is the outcome of a cross contaminated sample.

Trust the readings from the KHD as it will give you more repeatable results than the checker and is not susceptible to the common factors which alter the end-result of this kind of test kit. If you are more comfortable seeing the results from a conventional kit vs. a lab grade instrument, you can use the KHD adjustment tool to get the numbers to match.

Vinny, if the kHd is reading the reference sample at 6,5dKh it is one full degree off of the Reference solution so not sure if I should trust its measurements...?

 

[Vinny@GHLUSA]

Then that means you have a discrepancy somewhere in your KHD settings; sample tube volume, pump head calibration, etc.

 

[VJV]

Then that means you have a discrepancy somewhere in your KHD settings; sample tube volume, pump head calibration, etc.

Just last week I calibrated the sample and reagent dosing heads, and also calibrated the pH probe. I will try that again to see if it makes a change. My total water sample line measures 216,7mm, and I also have a filter attached to the tubing.

 

[VJV]

So, I have finally sorted out the issue and got it working again (reading within 0,1dKh of my Hanna Checker as before). Before I get into the solution, let me lay out the series of issues/reasons and solution I had:

1 - KH Director began to register extremely high figures (dKh of 14!!) while the Hanna Checker did not show an increase from the 8,5dKh where it had been at. REASON: never really found out. Could it be the sample water pump rollers (they were squeaking and filled with a black dust when I opened them)? Was it an issue with the new reagent bottle (although the first test after changing did not show an increase), air got trapped in the reagent tube perhaps?.I do not know.

SOLUTION: Cleaned the dosing heads of the Doser 2.1, re calibrated the pH probe, calibrated the dosing pumps.

PROBLEM: Now the kHD was consistently showing 1dKh below my Hanna Checker at 7dKh.

CAUSE: after going into GCC I noticed that the reagent pump calibration was showing 4,0ml/minute instead of 4,6ml/minute. (it took me more than a week to get to this point). I do not know why but when I calibrated the pump in the GHL App and entered the 4,6 it did not recognise it and switched to 4,0.

SOLUTION: In GCC made sure that the calibration was at 4,6ml/min after saving. Now it is showing consistent results again.

So all is well that ends well. When will GHL finally come out with push notifications (iOS please) so we can actually finally be able to sleep better knowing everything is ok...