Test kits for Alkalinity

[Ryanouw]

I’m having a bit of a head scratching moment I’ve tested my alkalinity and with 3 test kits and are all receiving different numbers...

I’ve just purchased two new test kits

Hanna Alkalinity Checker and it tested 194ppm
Which is 10.8
It confuses me since the I just bought a new

Salifert Alkalinity test kit and it tested at 8.0dkh I’ve tested it multiple times and it’s testing 7.3-8.0

This afternoon I used the Red Sea Alk test kit and it tested close to 10.7-8

Since the Red Sea and Hanna Checker are very close should I just assume it’s that and forget about the Salifert test kit

 

[windemerejack]

I had the same issue a bit ago, my hanna and red sea both saying approx. 9 -10dkh and my salifert was saying 8, I got some 7.5 standard solution and tested each test kit 3 times on that, results were hanna 9.5, 9.3, 9.6, red sea 9.1, 9.6, 9.6, salifert 7.3, 7.5, 7.5.
Needless to say I just use salifert test kit for kh, in fact I use salifert for everything except phosphate.

 

[Prevailing Reef]

I personally use Salifert for alk.

Always been the most consistent for me.

I use to confirm my Trident is working correctly.

 

[Ryanouw]

I had the same issue a bit ago, my hanna and red sea both saying approx. 9 -10dkh and my salifert was saying 8, I got some 7.5 standard solution and tested each test kit 3 times on that, results were hanna 9.5, 9.3, 9.6, red sea 9.1, 9.6, 9.6, salifert 7.3, 7.5, 7.5.
Needless to say I just use salifert test kit for kh, in fact I use salifert for everything except phosphate.

So your Salifert test kit was reading the correct or wrong numbers?

 

[windemerejack]

Salifert was spot on, it should be reading 7.5 and it did, the other 2 was way out

 

[PatW]

As far as I understand it, test kits do not purport to give you absolutely accurate results. They are best for detecting changes in a parameter.

If you want an accurate result, you need to run the test kits against a standard curve .... that is a set of standards of different known values so you can correct the reading your test gives you. But for our purposes, knowing the direction of change and the approximate magnitude is good enough to guide dosing.

Bulk Reef Supply did a you tube video of ALK test kits. They like Hanna the best with Salifert the best inexpensive one.