Salifert v. Seachem Ca Test Results

[Shoestring Reefer]

IF YOU HAVE TIME TO ARGUE WITH EACH OTHER YOU HAVE TIME TO CRITIQUE MY APPROACH!

Habib-does my approach look ok?

leebca-Can you come up with a better salt water standard? Other than "just use SeaChem's" or "go get a new job at a lab and steal some reagent-grade chemicals and do personal stuff on company time with company equipment (hmmm...like me right now)"? Pee or get off the potty. Shooting down other people's ideas is a great way to kill time, but we need answers!

I guess you can just mix up your own standard and do your own thing with it, but one person ordering a dozen different tests and finding out how they are similar or different is a great way to prove that one person has a hard time using one brand of test, and spend a few hundred bucks in the process. But it's your thing, go with it!

 

[Habib]

Shoestring,

One can buy e.g. Atlantic water with 35 PSU salinity for such purposes.

It costs a few hundred dollars.

There are more options but I did not want to divert the direction of this thread.

If you start a new thread then you can count on my input.


but one person ordering a dozen different tests and finding out how they are similar or different is a great way to prove that one person has a hard time using one brand of test,

One of my concerns.

I know that I personally have difficulty doing another brand's test and have to practice several times first before I can draw some conclusions.

 

[BeanAnimal]

I just want to know whos tests are accurate with regards to the water in OUR tanks. I also want to know whos tests are not to be trusted. I would even be happy knowing that brand X was 25ppm to high every time... at least it would be a reference point.

 

[javajaws]

I know that I personally have difficulty doing another brand's test and have to practice several times first before I can draw some conclusions.

Habib, Have you tested the Seachem test on your saltwater standard? If so, what was the result?

Also, do you have a FAQ or something that could help us to get better accuracy and/or more consistency when using the Salifert tests? Not that the included instructions are bad or anything...I'm just looking for additional tips.

 

[Habib]

Habib, Have you tested the Seachem test on your saltwater standard? If so, what was the result?

Also, do you have a FAQ or something that could help us to get better accuracy and/or more consistency when using the Salifert tests? Not that the included instructions are bad or anything...I'm just looking for additional tips.

I don't know how consistent the Seachem kit is. I have one but that one is one of their older versions requiring to filter the water.

I have ordered one but don't know when it will arrive.


Also, do you have a FAQ or something that could help us to get better accuracy and/or more consistency when using the Salifert tests? Not that the included instructions are bad or anything...I'm just looking for additional tips.

It is very high on my to do list.

 

[Shoestring Reefer]

Shoestring,

One can buy e.g. Atlantic water with 35 PSU salinity for such purposes.

It costs a few hundred dollars.

There are more options but I did not want to divert the direction of this thread.

If you start a new thread then you can count on my input.

New thread, and thanks all for the hijak!

 

[BeanAnimal]

hijak?

Habib, where are we at with explanations or comparissions of the different tests? I am still 7 pages into this thread and have only gleaned the fact that different companies may use different standards and calibration procedures. I have also learned that multi mega dollar test instruments may be worthless becuase the starting point is not known and the procedures are questionable?

Am I to surmise that Salifert is standing by the notion that the kits are accurate and the others are all "off" to some degree. I am not being a smartass, nor am I trying to infer that you are being dishonest or avoiding the matter at hand. I am just no closer to an answer than I was at page 1. I am convinced you are on "our" side and not trying to sell low grade reagents/kits as high end reef chemistry.

Bean

 

[Habib]

Lee,

I hope you are not offended by it but I think you lack, like many chemists and people in general, knowledge of marine chemistry.

So let me hand over a few things since you might not have the possibilty to search for it.

You doubt the consistancy of the ratio between the major elements in seawater.

Bommer posted something about it and so did I but somehow you still don't trust it.

So here is a bit more:

Historical Measurements of Composition of Major Components of Seawater
Bergman (1779) made the earliest chemical analysis of seawater

Marcet (1819) was the first to suggest that the relative composition of sea salt is nearly constant (the first law of chemical oceanography)

Forchhammer (1865) made first reliable measurements of major components on several hundred surface waters from all parts of the world.
Dittmar (1884) analyzed 70 seawater samples collected at various depths for the major oceans during the cruise of the H.M.S. Challenger (1873-1876).

Lyman and Fleming (1940) recalculated Dittmar's results using modern atomic weights

Cox and Culkin (1966) made measurements of major components of waters collected through out the world as part of salinity study.

Riley et al. (1967) made measurements of major components of waters collected through out the world as part of salinity study.



Relative Composition of Major Components of Seawater

gi/Cl(ââ"šÂ¬Ã‚°)
Solute A B C D
Na+ 0.5556 0.5555 0.5567 0.55661
Mg2+ 0.06695 0.06692 0.06667 0.06626
Ca2+ 0.02106 0.02126 0.02128 0.02127
K+ 0.0200 0.0206 0.0206 0.02060
Sr2+ 0.00070 0.00040 0.00042 0.00041
Cl- 0.99894 -- -- 0.99891
SO42- 0.1394 -- 0.1400 0.14000
HCO3- 0.00735 -- -- 0.00552
Br- 0.00340 -- 0.003473 0.00347
CO32- -- -- -- 0.00083
B(OH)4- -- -- -- 0.000415
F- -- -- -- 0.000067
B(OH)3 0.00137 0.001002

Ã¥ = 1.81484 1.81540


A. Dittmar as recalculated by Lyman and Fleming.
B. Cox and Culkin (1966)
C. Riley and Tongadai (1967); Morris and Riley (1966).
D. Millero (1996).



If you still don't trust it do some searches or please show it to be incorrect.

 

[freddie40]

Habib,

Today we cannot properly calculate Calcium levels based upon different test kit, yet you site articles as old as 225 years as proof???? Give me a break.

Lee, I cannot wait for your results.

Dave

 

[Habib]

Habib,

Today we cannot properly calculate Calcium levels based upon different test kit, yet you site articles as old as 225 years as proof???? Give me a break.

Lee, I cannot wait for your results.

Dave

Lee,

You can measure the calcium propely by using the right kits.
I leave it upto you or anyone else to decide which is right.

Don't forget that I gave actual results of a representative batch using a certified standard. I went further and used also natural seawater of which the calcium content is known. We do a LOT more tests to make sure it gives the correct value.

Having said that, I was showing that the consistancy which was discovered more than 100 years ago still holds. It is science which has proven to be correct by many researchers over more than 100 years.

 

[BeanAnimal]

freddie:

As a "technical analyst" you should be ashamed of your lack of logic. If it was a single 225 year old article, I would be leary... but he listed an entire bibliography of articles and a mountain of supporting evidence. Did you notice that some of the modern day articles used modern day science to re-prove some of the older science?

Furthermore, the context of the latest posts is that of seawater calcium concentration and not the accuracy of his kit (the basis of this thread). He is simply showing the evidence that he, AND LIKELY most labs, would use to verify a NSW sample.

I am not a chemist or analyst and figured this much out.

Your post is a useless flame and gets us no closer to answering why these kits differ from each other. So give us a break....

Bean

 

[Habib]

EDIT:
I was typing while BeanAnimal was posting. This post was an addition to my previous post.

Besides that I also showed that hobbyists find calcium values in their saltmix as has been measured by others using different techniques or as claimed by the manufacturer (and I assume the manufacturers did not use Salifert)

I also showed that others find plausible values for natural seawater from various locations using the Salifert.

Mr. Quality did some tests and posted them here on RC.


Also the salt Lee is using (Red Sea) has shown in a salt study the calcium content Lee is finding.

I find the same.



There are thus real data using standards, there are data by others to support this and there are data that match with specifications of various saltmixes.

I'm sure there is a lot more to support what I'm saying.

 

[Obi-dad]

I think the 'consistency of natural seawater' has little to do with the fact that we are getting different results on tank saltwater from different test kits.

 

[Habib]

freddie:

As a "technical analyst" you should be ashamed of your lack of logic. If it was a single 225 year old article, I would be leary... but he listed an entire bibliography of articles and a mountain of supporting evidence. Did you notice that some of the modern day articles used modern day science to re-prove some of the older science?

Furthermore, the context of the latest posts is that of seawater calcium concentration and not the accuracy of his kit (the basis of this thread). He is simply showing the evidence that he, AND LIKELY most labs, would use to verify a NSW sample.

I am not a chemist or analyst and figured this much out.

Your post is a useless flame and gets us no closer to answering why these kits differ from each other. So give us a break....

Bean

Thanks.

Allow me to add that I have constantly addressing the 25% difference. I'm not addressing differences by a few perecent. Which, BTW, I could also address but would get even more technical.

 

[Habib]

I think the 'consistency of natural seawater' has little to do with the fact that we are getting different results on tank saltwater from different test kits.

Different brands can produce different values and some brands also depending on how old the kit is.

I have seen some testing but I'm always sceptical about it because it is difficult to check if they used all the kits properly or did not make some "stupid" mistakes.


I once was invited to bring kits and also other brands would be there and hobbyisyts would measure NO3, PO4 and alk (and perhaps a few more parameters) using some "standards" a lab technician and reef hobbyist had prepared.

It was a major fiasco and I was glad I was there to see it happen.

 

[GTR]

I think if we can get beyond the 25% difference those small differences can be writen off as user errors.

With the difference from the old to new test Habib that's really all I could do. Never really sure if I did the old one wrong or the new one wrong. Just finally came to the realization that I'd never really know.
I have 2 other brands of CA test kits with less resolution and they read as close as I expect they would. Not 25% off BTW.

SteveU

 

[Boomer]

Bean :thumbsup:

Hab you left out a few ref but I do not think I need to list just moooooore of them. I mean how many times does one need to assay NSW and get the same resuts before it is not questioned :lol:

lack like many chemists and people in general, knowledge of marine chemistry

I wish I had a quarter for every time I have said that.

Seawater chemistry is't FW chemistry i.e., measure CO2 in FW, no problem easy, now try that in seawater with a any kind of kit or "wet-measurement". To this day know one has developed a test kit to measure CO2 in seawater, can't be done. And I do not care what HACH or LaMotte say Matter of fact it can only be accurately measured with a pCO2 probe.

 

[boxfishpooalot]

Bean :thumbsup:

Hab you left out a few ref but I do not think I need to list just moooooore of them. I mean how many times does one need to assay NSW and get the same resuts before it is not questioned :lol:

lack like many chemists and people in general, knowledge of marine chemistry

I wish I had a quarter for every time I have said that.

Seawater chemistry is't FW chemistry i.e., measure CO2 in FW, no problem easy, now try that in seawater with a any kind of kit or "wet-measurement". To this day know one has developed a test kit to measure CO2 in seawater, can't be done. And I do not care what HACH or LaMotte say Matter of fact it can only be accurately measured with a pCO2 probe.

Whats a pCO2 probe? can theese be bought for aquauims and I bet they cost an arm and a toe.:lol:

 

[Boomer]

They will cost you both arms and both legs, toes included :lol: It is a special probe that Dr. Frank Millero uses, that measures CO2 like a pH probe. See the "p" like in pH

Here is his website, Randy and I have brought up his name many times and most of Randy's articles have him as a ref and often with links.

http://www.rsmas.miami.edu/groups/jmc/fla-bay/fbay.html

 

[RustySnail]

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