Salifert test kits accuracy

[reefandfish85]

So I have Hana testers but I got Salifert test kit just to compare and today I tested my alkalinity with Salifert which showed 9.6dkh, Hana 8.2 dkh and then I tried API that was at 8.5 dkh, I did these tests 3 times in a row for all them and always same results. Is Salifert that much off ? which one should I trust ?

 

[NanoSteam]

Salifert has been my go to for calcium, Mg, and Alk and has tested fairly accurately for me based on what my salt manufacture says it mixes too and haven't had issues in the few years i've used them.

I'm assuming they are not expired? (should be an expiration date sticker on the box)

 

[Dan_P]

So I have Hana testers but I got Salifert test kit just to compare and today I tested my alkalinity with Salifert which showed 9.6dkh, Hana 8.2 dkh and then I tried API that was at 8.5 dkh, I did these tests 3 times in a row for all them and always same results. Is Salifert that much off ? which one should I trust ?

Your question cannot be answered without testing an alkalinity standard with each kit. Opinions are pretty useless.

 

[reefandfish85]

Do you always check all of your test kits with standard solution before you test ?

 

[reefandfish85]

Salifert has been my go to for calcium, Mg, and Alk and has tested fairly accurately for me based on what my salt manufacture says it mixes too and haven't had issues in the few years i've used them.

I'm assuming they are not expired? (should be an expiration date sticker on the box)

all the test kits are new

 

[PatW]

I test ALK with Red Sea Pro, Hanna, and Salifert, In my experience, they all go vary on the results. Hanna and Red Sea tend to be pretty close to each other and Salifert is a DKH unit higher. But I am mainly interested in my ALK level being constant and keeping it around a certain point (DKH). Any of the three tests will do it.

So as far as precision (reproducibility of the reading) all the tests I mention are about the same. Accuracy is how close the test is to the ACTUAL value of the parameter. Now for this, I would need a standard. And I do not have an ALK standard. I could make one. Heck I can use Soda Ash in RODI water and look at the dosing equations on adding the amount I need for a certain level. I just have not bothered.

For accuracy, they get within the ball park. For my purposes for acropora coral, they are close enough. And close enough is all that I am interested in.

There are times when I miss the days when I had access to laboratory equipment.

 

[Reef.]

So I have Hana testers but I got Salifert test kit just to compare and today I tested my alkalinity with Salifert which showed 9.6dkh, Hana 8.2 dkh and then I tried API that was at 8.5 dkh, I did these tests 3 times in a row for all them and always same results. Is Salifert that much off ? which one should I trust ?

You are probably overshooting the end point on the salifert, here is a good thread on why, the first post covers it.
Also having a test kit that will read the same lvl each time is just as important, worth running a few tests to see which gives the same result using the same sample of water, doesn’t really matter if the accurate reading is 8 or 7, but that each time you run the test it gives the same result.

Alkalinity titration endpoint pH & Salifert endpoint color

TL;DR: The endpoint pH is 4.41, and the endpoint color is that "lavender" color I've been telling people about. Over the years, there have been many threads on R2R and other forums debating a couple of basic details relevant to testing for alkalinity in reef aquaria. One of the most...

www.reef2reef.com

 

[Uncle99]

Not sure I would use the term off.
Salifert is a ballpark number. That’s why $25 bucks.
Hanna Alk, Nitrate and Phosphorus checkers have proved overtime, to me, to give good results but at twice the cost.
On the other hand, Hanna CA, and Low range nitrate I tossed in the trash..

My Salifert test kit shows nitrates at 5ppm when Hanna shows 11.7ppm, ICP confirmed the Hanna was closest at 13ppm. That puts the Salifert out 8ppm.

 

[NanoSteam]

Moral of the story is all of our "hobby grade" testers are just that, for hobbyist's and not professionals. I've had great results over the years sticking to one test kit brand and measuring for consistency/stability rather than chasing a specific number. Of course credit to the Hannah checkers for being as close to accurate as we can reasonably get.