KH Guardian Accuracy

[morpheas]

FYI, it is easy to do an accurate alkalinity test (assuming you can measure volume or mass accurately, and have a pH meter) if you want to evaluate the accuracy of this device or any kit.

I describe it here:

A DIY Alkalinity Test: By Randy Holmes-Farley - REEFEDITION
http://www.reefedition.com/a-diy-alkalinity-test-by-randy-holmes-farley/

I have actually performed the exact test to verify which of the salifert or Hanna were correct and that's how I found out that salifert was the one being closest. It's a great test procedure and good to have the ability to run any time...

 

[JonasRoman]

I have actually performed the exact test to verify which of the salifert or Hanna were correct and that's how I found out that salifert was the one being closest. It's a great test procedure and good to have the ability to run any time...

Salifert is for sure a very suitable test to being a reference towards other methods/machines/tests, as the Salifert is exactly that sort of comparing test that Randy suggests. The Salifert hava an acid of 0.022N(that is not a secret, it is easy to calculate that from the included table). The only weak point is the color change, and as I have done around 1000 salifert tests last months I can tell you that you shall stop titrating at the absolut very first colour change, thus when it turns violet. If you measure the pH of that water, when turning to violet, you will find that is is very near around 4.2, thus the end titration point (approx) for HCO3 in marine-water. So when I for instance compare Hanna checker and Salifert I for sure rely more on Salifert:)

 

[tdg0910]

FYI, it is easy to do an accurate alkalinity test (assuming you can measure volume or mass accurately, and have a pH meter) if you want to evaluate the accuracy of this device or any kit.

I describe it here:

A DIY Alkalinity Test: By Randy Holmes-Farley - REEFEDITION
http://www.reefedition.com/a-diy-alkalinity-test-by-randy-holmes-farley/

Thanks Randy, I'll give it a try.

 

[JimWelsh]

Salifert is for sure a very suitable test to being a reference towards other methods/machines/tests, as the Salifert is exactly that sort of comparing test that Randy suggests. The Salifert hava an acid of 0.022N(that is not a secret, it is easy to calculate that from the included table). The only weak point is the color change, and as I have done around 1000 salifert tests last months I can tell you that you shall stop titrating at the absolut very first colour change, thus when it turns violet. If you measure the pH of that water, when turning to violet, you will find that is is very near around 4.2, thus the end titration point (approx) for HCO3 in marine-water. So when I for instance compare Hanna checker and Salifert I for sure rely more on Salifert:)

I think of the Salifert endpoint color as more of a "lavender" color, but Jonas is correct that if you wait until it turns more orangish/pinkish, then you have overshot.

 

[traxxonwaxx99]

So has anyone had an issue with the KHG reading higher and higher with each test? I ran 5 tests when initially setup. Each came back at 6.9dkh. I have not begun dosing anything yet and over the past 2 days, it’s consistently gone up slowly with each reading and now it says 7.36. Not sure what the problem is.

 

[Jason_MrFrags]

The continous accuracy of the khg has always been in question. That's why I sent mine back and got an alkatronic

 

[tdg0910]

Thanks Randy, I'll give it a try.

Randy,

I tried the DIY with 250ml of tank water, I needed 6.6ml of acid to get me to 4.5. For reference, what would you say my alk is? 7.8?