Problem with GHL calibration fluid 50mS

[mdanielse]

Dear, GHL

I recently purchased 2 bottles of your 50mS(at 25C) calibration fluid(Chnr: 112212L, 11/2014).
When I compare the values with the AquaMedic and Sera calibration fluids, also 50mS at 25C then I notice a difference of 3,8mS.

The calibration fluids where all the same temperature, but this does not even matter because the measurements have been done with electronics temperature correction. I would expect to find 3 measurements which are the same, The AquaMedic and the Sera values are the same, the GHL is different. The AquaMedic and Sera fluids are also new, fresh from the supplier, so no old or half full leftovers.

All and all the real readings of my aquarium are better(when compared to my refractometer and aerometer) when I calibrate with the Sera or AquaMedic then when I calibrate with the GHL fluid.

Am I doing something wrong or is there a faulty batch of GHL 50mS in circulation

Please investigate and respond

With Kind Regards,
Jack

(Sorry,my mistake this topic should be transfered to the Englisch section)

[Matthias]

I don't know if and what goes wrong with your calibration and/or measurement but I don't think we have a faulty batch, we receive the fluids from a laboratory in Germany, each batch comes with certifications and sample measurement are made

it is your decision if you trust other's companies fluids more than GHL's products, I don't think we can solve this here

[mdanielse]

Hi Matthias,

It is not a matter of trust, it is just that it is strange that the GHL value is different than the other two brands(which is not necessarily a bad thing, because the other two brands can also be wrong). The thing that worries me is that when I calibrate with the other two calibrationfluids the aquarium measurements are closer to the comparisonmessurments that I took with my refractometer and earometer(floater type).
The only thing and I am looking for is a way to explain this.

And things can go wrong sometimes, we are all human. For instants there is a batch of AquaMedic 50mS fluid, but what is in the bottle is 100mS. There first reaction was also, "our 50mS fluid is perfect" but al in al it was not.

Perhaps there is a other way to check the calibrationfluids, which I have not thought at?, or is the only way to send it to a laboratory?


Kind Regards,
Jack

[Matthias]

so, meanwhile I personally took 15 bottles out of our stock and tested them

all of them had perfect readings -> I really doubt that there is a problem with our fluids

[mdanielse]

Hi Matthias,

If I may ask.....
How did test the 15 bottles calibrationfluids, what did you use as reference..... or did you check them against each other and then they all had the same value. Was there also a bottle from the batch I had?

Greeting,
Jack

so, meanwhile I personally took 15 bottles out of our stock and tested them

all of them had perfect readings -> I really doubt that there is a problem with our fluids

[Matthias]

we use a calibrated resistor-meter and do the tests with the fluid @ 25°C