Salifert v. Seachem Ca Test Results

[leebca]

I have both the Salifert and Seachem calcium test kits. I've repeated the tests several times on the same water. I've been extra careful on subsequent testings to be sure of the endpoint.

Each time the Salifert test results is 100 ppm higher than the Seachem (350 v. 250). Seachem results on freshly prepared salt water (from mix) is also different by about 100 ppm. Hard to believe that new salt would have that low of calcium at 1.025 sp. gr. and 75F.

Anyone know why the difference? Which one to make calcium additions to?

Any help, insights, references or ideas would be greatly appreciated. It's a little tough to make additions when working with a + or - of 40%.

[Randy Holmes-Farley]

The Seachem kit includes a standard. Did you test it with either kit? I'd try both that way, if you still have the standard.

[leebca]

You're too smart for me, Randy!

I put that bottle aside wondering why I would be needing it.

I tested both. The Seachem came within 10 ppm of their standard, the Salifert was 80 ppm lower than the standard.

Thanks!

[Randy Holmes-Farley]

You're welcome.

Happy Reefing.

[leebca]

It was just pointed out to me an error in my last post. The Salifert test came out 80 higher (not lower) than the Seachem test (in ppm). Sorry.

I repeated the Salifert test on the Seachem standard. This result came out to be 460ppm Calcium. (The standard is 390ppm Ca). This second test came out 70ppm higher than the Ca standard.

[BeanAnimal]

This does not speak very well for the salifert kit... I was under the impression that the salifert kits were the best on the market?

Is there a "list" or "test" of test kits for each parameter so that we can mix and match our tools to get the best results?
Bean

[leebca]

Salifert best? I don't think so.

IMHO the LaMotte, Hach, and Seachem test kits are the best. They are followed by Hagen. Behind that is Salifert and slightly further down the line is Red Sea and a few others. I've used all that I've listed above during the past year.

The problem with measuring Magnesium --- I can't find anything other than a Salifert kit. But for Ca I began with Salifert and then found the Seachem kit. I have used the Hagen Ca and LaMotte Ca also. I liked the Seachem endpoint the best.

[Randy Holmes-Farley]

In this instance, one is also assuming the standard is accurate.

[leebca]

Absolutely! PLUS that each test is performed correctly.

A Seachem standard against a Seachem test kit is somewhat a bit of the fox watching the hen house. I have other Ca test kits I'll try the standard with.

[leebca]

I tested the Seachem standard with other Ca test kits.

So far the data looks like the following:

Seachem standard is marked 390 ppm

Test Kit ......... Test 1 (ppm) ............ Test 2 (ppm)
Salifert ................. 470 ...................... 460
Seachem .............. 380 ...................... 385
LaMotte ............... 392
Hagen .................. 440 ...................... 440

My Red Sea master kit was outdated and I tossed it about a week ago.

The Hagen test 'suffers' (IMO) from a touchy reagent #2 that has to be shaken well before each use. I found that I get more consistent results when, after sitting for a while, that I waste the first two drops of #2, then use what's behind the spout. I also believe that the color of the Hagen test is too dark. It could easily be half that intensity. It makes the endpoint hard to read. But, I read it twice at the same place.

I think the Seachem test has the easiest endpoint to see.

The LaMotte test kit uses a pill for the indicator color. It takes a few minutes to disintegrate (which the directions require you to make sure it does), making this test the most time consuming of them all.

Both Seachem and LaMotte require that your sample to be tested be diluted in the test vial. Not difficult; time consuming; maybe this improves the endpoint and titration.

All tests are titration tests. I don't watch test costs closely, but a column of cost/test might be useful.

Maybe it would be a good idea to have a permanent thread with such info as the above for many test kits for different water chemistries?

[BeanAnimal]

I also feel that a sticky with this information should be created. It may even force some of the vendors to put better quality controls on their test kits. It is a shame that this hobby is saturated with so many sub-par items. I understand the quality vs cost ratio, but at some point junk is junk, not matter how much it saves you.

Do you happen to have any experience with the aquarium pharmaceuticals kits? This is what most my local LFSs sell (or red sea).

Bean

[Randy Holmes-Farley]

A large test of many test kits by many aquarists with a known standard would be a great idea. I'm a little hesitant to sticky results of s single set of tests as being representative, however.

[leebca]

My experience with Red Sea test kits is that they are too subjective. Their color references are not sharp enough to give reliable quantitative information. I'd put most of their tests at the end of the list of preferred test kits.

I don't know the Aquarium Pharmaceutical brand you mentioned.

[leebca]

. . .single set of tests. . .

Not sure what this means. But, a group of people with their own Seachem standard can submit test results to a dated sticky which can be updated as test kits are changed. One sticky per chemistry analyzed.

[BeanAnimal]

I would like to see some kind of organization instead of a free for all. I know nobody really has the time to undertake this... or it would have already been done.

I fear that it will turn into one of those "look here for..." threads that ends up being 490 posts long and useless as a reference. Similar to the Ballast threads and acylics threads.

A better format would be a table (similar to the post above) with a culumn for each chem paramater and a row for each brand.

Maybe we could get a static group of experienced volunteers to sign up for the tests, instead of accepting random results from random RC members. A small sample of well done tests will likely be as usefull as a large set of random tests run by the masses.

If the results vary wildly within the same brand, we can then assume poor testing technique or poor quality control from the manufacturer. Something that could be further studied to determine the true cause.

If the results are similar within a brand, then it will become quite obvious what brands are suited to what tests according to their overall percantage of accuracy.

Bean

[MiddletonMark]

Sounds like an interesting thing to gather a reef club and do.

You'd think you could assemble 10-20 folks, all using their Ca test kit [whatever brand] + the exact same standard for all of them ... probably a little more useful.

Because unless we know the standard is `on', does not vary, and has nothing in it that would hinder one or another test ... using 40 different standards with 40 different reefers with 40 different test kits ... will take a lot of #'s and then statistics IMO to sort out some sort of useful conclusion.

A great idea though - I've always wondered [and been saddened] that so few companies go with some `standard' to test against [to see if you're doing the test right, the first time] as well as to check if it's old or not.
Funny thing is - when some others in my reef club and I got together to test salt samples a few months ago [posted results here] ... the Seachem Ca test kit read about 90-100 points low pretty much across the board as compared with 2 Salifert Ca test kits. At the time I assumed my nearing 2 year old kit had either gone old or the reagent dirtied/etc ... but now, I wonder.

[BeanAnimal]

what about simply using a single standarad and each volunteer mailing it to the next person on the list. In 2-3 weeks a decent amount of data could be collected.

Better yet we could volunteer Randy to provide a "known" standard to several people. These folks could then pass the sample on to a few other folks. If the standard concentration were not marked, then the results would not be biased. Randy (or a chosen person) could compile the blind results via email and compile the table. Because the testers don't know the concentration of the standard, the results would not show a bias.

Maybe to much to ask of Randy... but would be interesting.

Bean

[leebca]

A split blind sample, or group of two or three samples, would be optimal, I should think.

I should also think that the sample be salt water (to include likely interference). Either a known quantity by high tech measurement, or by adding known quantity to a sample void of the ingredient would be acceptable.

I don't think it should be done by a single club. It should be spread out across the continent, with different lots of the test kit and without a close communication or regional influence.

[Hobster]

FWIW

I have both the SeaChem and Salifert Ca test kits. I will be testing my tank tomorrow so I will use both and also test the SeaChem standard.

[leebca]

That's excellent. The problem with any set of results (like mine) is that it could be a fluke or bad test kit with one or more bad reagents.

[BeanAnimal]

I just had a look at the seachem website and their PDF intructions. I sure hope the instructions are more complicated than the actual tests. All of my tests kits are "fill to line and add drops type". One of them (calcium) is confusing as to the endpoint color, as it can be either side of 2-3 drops depending on how you look at it. At a step value fo 20.. that is up to 120 ppm error just reading the darn thing, let alone errors in the test itself.

My alkalinity test changes from blue to yellow and each drop is 1 dkH. A no brainer. The seachem kit instructions seemed VERY invloved for the alkalinity.

In looking at the Hach website... I see they have a digital titrator for $168. That seems kinda neat. The more I look, the more I become confused. A recomended test kit list would be a great value here.

Bean

[Hobster]

very true: Just adding mine to the list if you want to get some random samples from different areas. At least to see if mine is close to what you got.
We can get a general idea, but with many different individuals doing the tests with different lot#s I don't know if it would be statistically valid results.

[leebca]

BA,

Like I had posted: Both the Seachem and LaMotte test kits for Ca require a sample dilution. It is easy for Seachem. Just fill a vial they provide with distilled water and add it to the vial of the sample, then continue.

Like most directions, they can be a bit challenging at first, then after the 20th test, you're into a grove. When you look at the reagents and hardware provided, you can do it from memory and reading the reagent labels.

[leebca]

Randy,

Just realized that the calculator doesn't offer Dow Flake as a choice for Ca addition. That's what I have. How to convert which one?

Thanks.

[RustySnail]

One question regarding the testkit "error"...

What is the age of the Salifert kit(s) that are giving low readings? I had this problem a few months ago; but my Salifert kit was probably 3+ years old and I figured that it was just out-dated. The same happened with a friend's kit; we tested them against the Seachem standard to verify the Salifert kit(s) accuracy. The reason IMHO was that the kits had started going bad. There is also a question about the Seachem standard; but unless there is a way to make a standard we wont know if the Seachem standard is actually higher in Ca than it is labeled at. NSW -might- be a good thing to test/use as a Ca standard.