Hanna Alk Checker

[Boomer]

Just up recently

Hanna Instruments' Checkers: Alkalinity and Phosphate

http://www.advancedaquarist.com/2011/8/review

Off more than that 10 % like we thought.

 

[DustinB]

Ouch. Have there been any tests like this on a salifert alk kit? My salifert and hanna are right in line.

 

[JG1]

whats the correction factor for the alk checker?

 

[BigKahuna]

The results with the PO4 checker are quite impressive though:

The results generated by the inexpensive Hanna Checker are remarkably close to those reported by a $3,500 spectrometer.

 

[maysorum]

Ouch. Have there been any tests like this on a salifert alk kit? My salifert and hanna are right in line.

I agree, my Hanna and Salifert results have been close day after day. Here's today's numbers:

ALK
hanna 7.952
salifert 8.15

CA
hanna 439
salifert 445

 

[Boomer]

Yes Kahuna they are more than impressive

 

[Boomer]

John

Looks like add 50 % :lol: Reading 100 ppm add 50 ppm = 150 ppm

 

[BrassMonkey]

Ya I noticed mine was off cause my sps tank wouldn't drop below 171 ppm. With the above correction that means my tank was actually a at 6.77dkh. I don't trust my Hanna meter.

 

[jimsplace]

To be fair and before we all get up in arms about the Hanna checker, why not preform the same test using say a Salifert Alk kit? I would bet the results would be the same or worst.

 

[HighlandReefer]

Thanks for the update Boomer. :thumbsup:

Hobby grade test kits and $50.00 meters will be a problem for some time to come. :lol:

These are the main reasons why one should shoot for the middle of the recommended ranges.

 

[disc1]

I doubt its going to be the kind of thing that a single correction factor can fix. I'm hearing way too much about water with very different all content hiving the same reading on the Hanna.

 

[JG1]

John

Looks like add 50 % :lol: Reading 100 ppm add 50 ppm = 150 ppm

Your kidding? :eek1:

 

[JG1]

Somethings not right because my salifert kit reads about 1.2dkh HIGHER than my hanna

 

[Psyops]

Sometimes I feal like the more I learn, to more I realize that I don't know anything.

I guess that is good news for phosphate and not so good for Alk. It might explain how some people can keep good SPS tanks with higher phos numbers on Hanna readings.

Thank you for finding that post Boomer!
Alex

 

[doctorgori]

Sometimes I feal like the more I learn, to more I realize that I don't know anything.

yeah, well try sifting through those "Advanced Aquarist" articles using only avg IQ and a Cleveland Public Schools edumacashun ... I gave up after trying to enunciate "tiration" ...I didn't know whether to get "excited" or get embarassed...

typically I wait for the breakdown from post like the above

 

[Boomer]

OK, I need sot make some clarifications here as I jumped the gun somewhat

First, this is not really clear;

Looks like add 50 % :lol: Reading 100 ppm add 50 ppm = 150 ppm

That is the HACH going to the Hanna. So, from the Hanna to equal the HACH it is subtract 50 % HOWEVER, at what many run their Alk at 180 ppm = 3.6 meq / l = 10 dKH it is more like subtract 25% of Hanna reading. At the HACH 180 and the HANNA 240 mark. Hanna 240 x 25 % = 60 and 240 - 60 = 180.

But there is more here

Dana's link on Alk is not to Randy's link on Alk.

What is Alkalinity
http://www.advancedaquarist.com/2002/2/chemistry

From it:

The precise endpoint of a total alkalinity titration isn't always the same pH, but rather depends a bit on the nature of the sample (both its ionic strength and its alkalinity). For normal seawater, this endpoint is about pH = 4.2. In freshwater it depends strongly on the alkalinity, with an endpoint of pH = 4.5 for an alkalinity of 2.2 meq/L, and pH = 5.2 for an alkalinity of 0.1 meq/L.


Well, the Hach kit was designed for use in fresh water where the pKa of the bicarbonate is much higher than in seawater, and in that situation, it is appropriate. In seawater, however, it is marginal. My tank water took 3.4 meq/L to get down to pH = 5.03, and then an additional 0.4 meq/L to get down to pH 4.00. Consequently, this kit (and others with a similar dye mix) may be missing out on 10% of the alkalinity simply because it isn't titrating low enough. This difference obviously isn't significant to most reef keepers, but is something to keep in mind when doing such things as comparing test kits to standards (in seawater) or to each other.

So now we need to add 10 % to that HACH reading of 180 = 198

Now the Hanna is reading 18 % to high.

HACH = 198

Hanna = 240

240 x 18 % = 43 and 240 - 43 = 198

So, the correction error for the Hanna to get a better true value is :

Hanna - 18 % of reading at ~normal pH and Alk.

This is MY fault for NOT thoroughly reading th article and all that it does and did not involve. I will let Danna know.

Sorry guys

 

[ksed]

Good catch Boomer

Thanks for the clarification.

 

[JG1]

Are we now sure that hanna reads 18% high? This is across the board for all the alk checkers and not an individual one?

 

[JG1]

So if we're aiming for a 9-10dkh we should shoot for a 196-218 on the Hanna?

 

[Boomer]

JG

There is no absolute certainty here for me unless this checker was sent to Millero's labs, as to how far it is really off. Same for the Salifert or any other kit used for Alk. Alk testing is NOT an easy thing in Seawater. And all kit and metes are based on FW. The Salifert is suppose to be for seawater but I see issues with it also, as it reads even higher than the Hanna,at least form posts here. We CAN NOT go by what companies say.

This is across the board for all the alk checkers and not an individual one?

Just this one by Hanna

9-10dkh we should shoot for a 196-218 on the Hanna?

Yes, close enough.

Our issue is any of these kits or meters need to be sent to a REAL seawater expert for testing, such as Dr. Frank Millero, the leading expert on these issues.

So, to all guys here it looks like Alk is still a shot in the dark. Maybe Dana will run some new tests. I have PM him.