Hanna Alkalinity Discrepancy from ATI ICP

[george9]

Hi all,
Recently got an ATI ICP test back and my alkalinity showed 7.08, which is .52dkh lower than what I tested my alk to be with the Hanna checker on that same day. Margin of error on the Hanna is +-.3 and this .52 difference is outside of that range which worries me a bit.

What is the best way to verify accuracy of Hanna alkalinity checkers? There’s no way to calibrate them so do I have to accept that my real alk is likely lower than what my Hanna checker says forever? I’d likely want to keep my alk above 8.0 in this case to provide more of a buffer.

I tested with salifert which is a bit harder to get a reading down to .1, and it is somewhere in-between 7.1 and 7.6, it’s more like 7.3 to 7.4 which lines up fine with the Hanna checker specified accuracy.

I wouldn’t even be opening this can of worms if the ICP came back within .3 of the Hanna, but there may possibly be an issue with my checker. The reagent was a week old, and was kept in the fridge. I have never had discrepancies between reagent bottles this way.

Curious to hear thoughts, although I may be over-reacting here lol

 

[StatelineReefer]

Hi all,
Recently got an ATI ICP test back and my alkalinity showed 7.08, which is .52dkh lower than what I tested my alk to be with the Hanna checker on that same day. Margin of error on the Hanna is +-.3 and this .52 difference is outside of that range which worries me a bit.

What is the best way to verify accuracy of Hanna alkalinity checkers? There’s no way to calibrate them so do I have to accept that my real alk is likely lower than what my Hanna checker says forever? I’d likely want to keep my alk above 8.0 in this case to provide more of a buffer.

I tested with salifert which is a bit harder to get a reading down to .1, and it is somewhere in-between 7.1 and 7.6, it’s more like 7.3 to 7.4 which lines up fine with the Hanna checker specified accuracy.

I wouldn’t even be opening this can of worms if the ICP came back within .3 of the Hanna, but there may possibly be an issue with my checker. The reagent was a week old, and was kept in the fridge. I have never had discrepancies between reagent bottles this way.

Curious to hear thoughts, although I may be over-reacting here lol

You can use the Hanna reference solution to calculate if your checker has drifted. Many times this just comes down to not having a spotless cuvette, and the checker's eye picking up something you don't notice. If in doubt, try a new vial alongside your old one and see if the measurement changes.

 

[AstroCoral]

Hi all,
Recently got an ATI ICP test back and my alkalinity showed 7.08, which is .52dkh lower than what I tested my alk to be with the Hanna checker on that same day. Margin of error on the Hanna is +-.3 and this .52 difference is outside of that range which worries me a bit.

What is the best way to verify accuracy of Hanna alkalinity checkers? There’s no way to calibrate them so do I have to accept that my real alk is likely lower than what my Hanna checker says forever? I’d likely want to keep my alk above 8.0 in this case to provide more of a buffer.

I tested with salifert which is a bit harder to get a reading down to .1, and it is somewhere in-between 7.1 and 7.6, it’s more like 7.3 to 7.4 which lines up fine with the Hanna checker specified accuracy.

I wouldn’t even be opening this can of worms if the ICP came back within .3 of the Hanna, but there may possibly be an issue with my checker. The reagent was a week old, and was kept in the fridge. I have never had discrepancies between reagent bottles this way.

Curious to hear thoughts, although I may be over-reacting here lol

An ICP analysis does not check alkalinity. They are using a separate test kit on one of the three saltwater vials you send off to measure your sample’s alkalinity, it may potentially be more or less accurate when compared to your Hanna. Unfortunately I have not found a resource where ATI lists how they measure alkalinity in the sample water provided.

Edit: My belief is that consistency in alk measurements is a larger factor in coral health than a number of 7 vs 8 dkh.

 

[rtparty]

Whether you’re at 7.1 or 7.6dkh means very little. Like you said, keep alkalinity around 8dkh and you’re good. If your Hanna is actually off .5dkh, then you’re still at 7.5dkh and that’s a fine number to run. I’ve been running that alkalinity for close to 15 years now.

 

[exnisstech]

ATI couldn't even give me accurate results on RODI water so I would trust the Hanna. I sent two tests in from seperate tanks and they offer RODI tests included with their ICP so I sent two of those as well. RODI was taken from the same container at the same time but the test results were drastically different.

 

[X-37B]

I have the Hanna checker but use Salifert 95% of the time.
What alk levels are you trying to maintain as you need a range?
I run 6.5-7.5 with a target of 7.
The main thing is repeatability.
If Hanna is reading 7.5 and its actually 7 its not an issue, imo, as long as its within your set alk range.

 

[george9]

Im shooting for between 7.5 to 8.0 but may decide to bump it closer to 8.0-8.3 to keep more of a buffer. That way I can be sure I won’t touch below 7.0 in case I start getting when wonkier readings one day.

I guess I need to reach out to ATI to see what the error in their tests is. If the Hanna error and ATI error overlap then maybe there is no issue at all. I don’t know why I was considering the ATI test gospel but they all have error.

I will try using a new Cuvette for tomorrow’s test and see if that impacts anything.

The Hanna alk standards are a whopping $27 lol. After spending $50 on an ICP test and $75 on new alk reagents, I do not want to spend another $30 when I am not even having coral issues lol

I will reach out to ATI to see if they know their potential error and see how it overlaps with Hanna’s specified range.

I always end up falling down rabbit holes questioning the accuracy of all of my instruments after ICP tests. How do we know anything is truly accurate!!? Consistency and stability is key I suppose.

 

[AstroCoral]

Im shooting for between 7.5 to 8.0 but may decide to bump it closer to 8.0-8.3 to keep more of a buffer. That way I can be sure I won’t touch below 7.0 in case I start getting when wonkier readings one day.

I guess I need to reach out to ATI to see what the error in their tests is. If the Hanna error and ATI error overlap then maybe there is no issue at all. I don’t know why I was considering the ATI test gospel but they all have error.

I will try using a new Cuvette for tomorrow’s test and see if that impacts anything.

The Hanna alk standards are a whopping $27 lol. After spending $50 on an ICP test and $75 on new alk reagents, I do not want to spend another $30 when I am not even having coral issues lol

I will reach out to ATI to see if they know their potential error and see how it overlaps with Hanna’s specified range.

I always end up falling down rabbit holes questioning the accuracy of all of my instruments after ICP tests. How do we know anything is truly accurate!!? Consistency and stability is key I suppose.

Chasing numbers can lead to the downfall of a tank in my opinion, if your current setup is working then keep doing what you’re doing. The enemy of good is better.

 

[jda]

Pick one to trust and use. This process does need some faith. I put faith in Salifert Alk test kit - been around forever, as accurate as anything while being consistent, cheap and easy to use.

Segal's Law is all too prevalent in reefing.

 

[george9]

Chasing numbers can lead to the downfall of a tank in my opinion, if your current setup is working then keep doing what you’re doing. The enemy of good is better.

I wouldn’t say this is chasing numbers, just ensuring I am getting accurate readings!

Segal’s law is too real. Drives me absolutely crazy. Don’t get me started on how every thermometer I have says something slightly different.

 

[jda]

Right?

I would get a thermometer with mercury in it (or whatever mechanical substitutes that they have nowadays) and some salifert test kits. Consider those your standards - this is where I put my faith since truth is not gonna happen in this hobby. If I want to use a Hannah, then if it is constantly .3 higher than the Salifert, then it is .3 higher. I have a laser temp gun that is like .5 higher than my old thermometer, so I just subtract .5 degrees.

I would trust things that you do not control the least amount, so mail-away tests for me where who knows what kind of effort that you are getting on an alk test - probably some good days and some bad days.

 

[george9]

Right?

I would get a thermometer with mercury in it (or whatever mechanical substitutes that they have nowadays) and some salifert test kits. Consider those your standards - this is where I put my faith since truth is not gonna happen in this hobby. If I want to use a Hannah, then if it is constantly .3 higher than the Salifert, then it is .3 higher. I have a laser temp gun that is like .5 higher than my old thermometer, so I just subtract .5 degrees.

I would trust things that you do not control the least amount, so mail-away tests for me where who knows what kind of effort that you are getting on an alk test - probably some good days and some bad days.

I find it way too easy for me to get in the weeds trying to make sure my instrumentation is correct and then second guessing everything. I have 4 glass thermometers and they all show something slightly different between 76-79. Then of course the Hanna salinity pen shows something right in between all of the glass thermometers. I average them to set my a inkbird controller.

This ICP test showed my salinity as 35.0 versus my Hanna pen showing me 34.5 and that was about to set me over the edge until I realized if I was using SG mode, that would be a perfect 1.026 regardless. .5ppt difference is like .0004 points in specific gravity.

I sent an email to ATI just to get a little more info about how they test alkalinity to get a better feel for how accurate they think it is.
Heck, they may even use a Salifert kit themselves

 

[jda]

I had a way more zen experience in this hobby once I realized that there is very little facts or truth and that we do a lot of things based on faith. This might drive some folks crazy and I get that too.

Consistency > accuracy. However, for what we pay for most things, some darned accuracy might be nice too!