Salifert v. Seachem Ca Test Results

[leebca]

Sorry. I've been unable to log on for a couple of days.

Habib,

There may be a misunderstanding:

I am really amazed with what ease you trust (or is it trusted) a reference supplied in a hobby test kit but don't trust what are facts presented in the scientific literature and fully accepted by the scientific community.

I don't trust anything yet. I'm exploring. All I know is there is a disconnect. The pieces of the puzzle are not coming together. Test kits that claim to measure the same element are not agreeing.

I am just as skeptical as someone who proves the calcium concentration through calculation rather than direct measurement.

Producing high correlation coefficient and low s.d. does not mean that the result is accurate.

I said nothing about accuracy. The original quote which you posted and addressed was:

I have confidence in a machine's ability to measure something when I can count on a high correlation coefficient (r value) the standard curve generates.

I hope also to not offend, but you don't seem to understand the scientific difference between 'confidence' and 'accuracy.' Please read what I write more closely and if necessary, have a dictionary handy.

freddie40 posted what is a very short version of what would have been my reply to your second post to me. What part of "show me" rather than "theory" wasn't clear? Save thread space in the future on this, Habib. I can't use theory, or ocean or sea data, to measure the calcium in my aquarium. My aquarium system contains artificial seawater.

I think the above responds to posts to me on page 7 of this thread, from Habib. Moving along. . .

 

[leebca]

Still responding to posts to me on Page 7. . .

Shoestring Reefer,

If it can be chemically demonstrated that the test for calcium has no intereference from seawater composition, then a straight forward stand is possible, but our test kits aren't necessarily free from this effect.

It could be done, I think, by putting together the top 20 ingredients of seawater into a sample, including those compoenents that interfer with test kit results, with calcium free or known calcium content chemicals, then add a known quantity of calcium, then total it all up and hand in a standard. I'll check the other link (hopefully soon!).

 

[leebca]

I have recevied today the rest of the calcium test kits. I will be able to test this weekend. But, I will not have the AAS results for about three+ weeks. When they are in, I will complete the table.

I encourage others to do their own tests.

 

[jfinch]

What's wrong with mixing up a gallon of IO. Splitting it and spiking half with a known amount of dried ACS grade calcium chloride to increase this sample's calcium content by 50 ppm. Now test both batches. The kit(s) that I would trust should show this 50 ppm difference. The uncertainty in moisture content of the CaCl2 can't throw this off by more then a few ppm can it?

 

[Habib]

Lee:

I don't trust anything yet.

I'm glad to hear that. I had the impression that you trusted the reference. I'm glad to hear that this is not the case.


I hope also to not offend, but you don't seem to understand the scientific difference between 'confidence' and 'accuracy.' Please read what I write more closely and if necessary, have a dictionary handy.


I fully understand that. That's why I also said a few times that I'm addressing the large differnece of 25% and not a possible difference by a few percent from the actual (real) value.


From jfinch:

Splitting it and spiking half with a known amount of dried ACS grade calcium chloride to increase this sample's calcium content by 50 ppm.

Spiking to say 300 or 400 ppm will work not 50 ppm because the resolution of kits is not better than approx 10 ppm. 10 ppm of 50 ppm is 20%.

In the "other" thread I mentioned that one of the things we do is spike various marine samples (both natural and artificial ones) with knwon amounts of certified standards.

I think, but have not received the Seachem yet, is that the Seachem might essentially be a freshwater kit if the amount of DI or RO water one has to add is much more than the amount of aquarium water sample.

 

[boxfishpooalot]

Hey Habib,
Any thoughts on how you could manufacture a new calcium test kit that may cost a little more but possibly be more accurate? Maybee have some better chemicalls or somthing to better the life/stability/accuracy of it.

Tia box




O yea and I would not mind paying an extra 10-20 bucks for it either providing its got that extra accuracy. That is,if it already is accurate then there is no problem. But as we all know, better chemicalls cost more money, sooo.

 

[jfinch]

Spiking to say 300 or 400 ppm will work not 50 ppm because the resolution of kits is not better than approx 10 ppm.

I wondered about the resolution of the kits seeing that small difference. But spiking by 300 - 400 ppm would likely result in some CaCO3 precipitation which presents it's own problems. Maybe if the testing was done fairly quickly after spiking. I doubt an ASW sample with an overall calcium level close to 800 would have a long shelf life (as far as calcium is concerned). Do you spike samples by that much?

the Seachem might essentially be a freshwater kit

You know, that makes perfect sense. Why else would one need to dilute with RO water...

 

[leebca]

boxifhspooalot,

I know you didn't address your post to me, but, I can't resist. . .

You're presuming that the Salifert test kits isn't accurate or isn't accurate enough. I have no reason to come to either of those conclusions. I would answer the question with a question: What's wrong with the kit the way it is?

:rollface:

 

[Habib]

Spiking to say 300 or 400 ppm will work not 50 ppm because the resolution of kits is not better than approx 10 ppm.

I wondered about the resolution of the kits seeing that small difference. But spiking by 300 - 400 ppm would likely result in some CaCO3 precipitation which presents it's own problems. Maybe if the testing was done fairly quickly after spiking. I doubt an ASW sample with an overall calcium level close to 800 would have a long shelf life (as far as calcium is concerned). Do you spike samples by that much?

the Seachem might essentially be a freshwater kit

You know, that makes perfect sense. Why else would one need to dilute with RO water...

Spiking after doing the titration. It is not perfect but very close to it.

 

[boxfishpooalot]

boxifhspooalot,

I know you didn't address your post to me, but, I can't resist. . .

You're presuming that the Salifert test kits isn't accurate or isn't accurate enough. I have no reason to come to either of those conclusions. I would answer the question with a question: What's wrong with the kit the way it is?

:rollface:

I see nothing wrong with the kit the way it is. Actually I have a hagen test kit(mr cheap kit) and salifert calcium kits. Funny the hagen is close to salifert. One reads 390 and the other 400. So its not like this is a huge deal anyways.

I would just pay more for a kit. Lets say salifert basic calcium(the one alredy using) and salifert expert calcium.


I mean come on guys your not paying the cost of Hach or Lamotte!

 

[boxfishpooalot]

Salifert could say somthing like:

Introducing our new Salifert test kit. Expert calcium testing, the new improved calcium test kit for aquariusts with that extra little worry about calcium measurment.

Due to high demand, we have introduced our new kit with more stable chemicalls and reactants. This way you know your right on the nose. This kit is precsie +-.0000000001.(bare with me)

But, at the extra cost its gunna be well worth having, as you will never have another worry about being 40 points off.

The new kit has an extended shelf life......

blabla,
See my point?


So Hab, you interested in marketing the "expert calcium test kit" for those picky people out there?

 

[jfinch]

Spiking after doing the titration. It is not perfect but very close to it.

Dang! That's why I'm an engineer :lol: (ashamed that idea hadn't occured to me before ). :thumbsup:

 

[boxfishpooalot]

Hey, you guys were on a role! Dont let my posts stop you from discussing. I still want to know what you guys find.

Box.

 

[Boomer]

Lee

Methods of Seawater Analysis

Editied by Klaus Grasshoff, Klaus Kremling and Manfred Ehrhardt

632 pages

Wiley-VCH; 3 edition (May 25, 1999)

You will need + $300


Analysis of Seawater by T. R. Crompton

438 pages
Butterworth-Heinemann (July 1, 1989)

You will need $200

 

[leebca]

Boomer,

I'd rather put my money into a Hach system. Just bought the Hach Digital Titrator system. Have you found it can test anything more in saltwater other than: Acidity 100 to 4,000, Alkalinity 100 to 4,000, Ammonia 0 to 3, Carbon Dioxide 10 to 100, Chloride 2 to 100 ppt, Dissolved Oxygen 0 to 10, Hardness 100 to 4,000, Nitrite 0 to .5, and pH 4 to 10?

 

[Boomer]

You should have consulted me first:lol:

YOU CAN NOT measurer CO2 in seawater with ANY test kit

Carbon Dioxide 10 to 100

This is so funny,me Millero, Mowka and Callaway explained this to them years ago and they still make it :lol: So what is so funny ?

Carbon Dioxide 10 to 100 mg / l . NSW has only 0.5 mg / l. To get 10 ppm CO2 in seawater with the following @ STPS, with pH @ 8.3, you neeeeeeddddddddddd an Alk of 60 meq / l :rollface::rollface:


Hardness;

It looks like you got the wrong one. You want the TH and Calcium, Magnesium by the difference. # 20639-00 HAC-DT, 10 -4000 mg / l


Salinity/Chloride

There is also a Salinity DT 2- 100 ppt. This must be what you got, as there is no such thing as a Chloride kit 2-100 ppt, they are 10-8000 and 10-10000 mg / l. However, the Chloride kit and the Salinity kits are the same thing, as Salinity kits are measuring Chloride. This is an error on their part and LaMotte kinda', to be calling this Salinity, when in fact it is Chlorinity and NSW Cl = 19 ppt and S = 35 ppt. This is known as the Knudsen Method. More confusing, is that although it is measuring Chloride or Chlorinity, they have set it up so the numbers you get are expressed as "real" salinity as in 35 ppt NSW.


Others

There are others for the DT but I see know need for them; Chlorine (unless you want one). Iron ( but it starts at 10 mg / l but I suppose you could make diluted samples)


There is no need for an Acidity test kit. No need for things like Cr or, Volatile Acids, Acid-Base. Sulfite *may* be interesting. Have no idea about the Chelant kits, free- total.


I might add more on seawater stds. There are others

Normal Water NSW STD
Copenhagen Water NSW STD ( the most well known)
Wormley Water NSW STD

You should be able to find;

Standard Methods of the Examination of Water and Waste Water

All reported USA measurements/ =parameters must be by ONLY these methods. How nasty are they If you turn in a report that says 10 ppm NO3, you will get it back, as it must be in 10 N-NO3

 

[leebca]

Bopmer,

The test info came from the Hach site for FF-3:
http://www.hach.com/hc/search.produ...M05qSTBNemswT1NabmRXVnpkRmhTUVVKVk1RPT1Cag==|

Carbon dioxide: Why would they have included it in the saltwater test? What you wrote makes sense, but then why include it? Are they that 'insensitive???'

Hardness
Maybe it's a typo in the description? The kit is supposed to be for Saltwater. I see the product number on their site, but they don't list the product number in the FF-3 kit.

Fe has always been a bit of a joke to me. It should be in ppb, but kits all seem to measure ppm.

So you think the DT is only of value for: Hardness (if it's the right reagent set); Ammonia; Nitrite; and pH?

Well, I can always return it for a full refund (it's the policy fo where I ordered it from). It might be more economical to buy the DT and right Hardness reagent set, than the whole kit.

Have to get back to collecting data! Chow!

 

[Boomer]

Are they that 'insensitive???'

Yes, they do not listen, either does LaMotte. They asked me to prove it and I did and they still did not drop it. Like I said if CO2 in std seawater is about 0.50 mg/ l liter what good is a kit that starts at 10 mg / l :lol:

The kit is supposed to be for Saltwater

Yes, that is correct but way back when they came up with this kit nobody was interested in Ca and Mg only TH ( CA and Mag, plus Sr and Ba)

They have the same issue we are dealing with here on these threads, that me, Habib and Randy are trying to throw out, i.e., FW is not SW and many think analytical procedures are the same for both....NOT for many parameters

So you think the DT is only of value for: Hardness (if it's the right reagent set); Ammonia; Nitrite; and pH?

No, those that I listed are the one would want, i.e.


Alkalinity, Salinity (Chloride ), Dissolved Oxygen, Total Hardness, plus Ca and Mg. ( the only ones that kit that are DT other than the useless CO2, in that DT-Kit)

And I forgot and YOU did not read carefully enough about this kit FF-3 There is no such thing as a DT for nitrite, nitrate or pH. The are color cube colorimetry. And who in god's name would want a pH kit that tests to .5 pH units. The best one out there is the FasTest/SeaTest by Aquarium Systems, unless you have a meter.

Go back to the link and notice this

Digital Titrator titration: ****color disc colorimetry****

Click on Download below to get the manual in PDF or here >>

http://www.hach.com/fmmimghach?/CODE:243090778|1

When I bougth mine I custome desinged it with with the HACH Products for Analysis book in front of my face

 

[freddie40]

You want to talk about really poor customer service...chack out this thread: http://www.reefcentral.com/forums/showthread.php?s=&threadid=658645

 

[leebca]

Boomer, Still confused

Not sure if "what you want" is what's available. Mg and Ca aren't in the kit. Are there reagents for the DT for those?

So the tests (Ammonia nitrogen, nitrite-nitrogen, and pH) are color comparatives, not endpoints? I don't want/need the nitrite and pH (anyway). Ammonia might have been nice, but I can get it from the LaMotte colorimeter. I don't think there was any mention of nitrate for this equipment.

Thanks.

(Done about 70% of the Ca testing. Still working on it.)