Ca Test problems
- Thread starter stilmas
- Start date
Actually heh, if you look closely you should notice that the reagents are pretty much the same. Salifert makes the reagents for the SeaTest Calcium test. So I'm pretty surprised you see that great of a delta.
Are you getting a distinct color change from the SeaTest or is it turning from pink to purple and you are adding a few extra drops? When you get to about 24 drops slow down, give each drop about 1 full minute or longer to react.
Are you getting a distinct color change from the SeaTest or is it turning from pink to purple and you are adding a few extra drops? When you get to about 24 drops slow down, give each drop about 1 full minute or longer to react.
I'm giving it a few extra drops to turn it from purple to pure blue like it says in the instructions. Not waiting a full minute though, the instructions didn't mention anything about that. Thanks for the info, but in this case, if I do keep getting different readings which one do you recommend that I trust? Thanks again!
It looks like they are both reading the same, just some operator induced error on the SeaTest one (the purple to blue change is a ***** sometimes and it takes a practiced eye).
Whichever is easist for you to use and it sounds like Salifert is the winner. When you have finished these kits, you may want to try Tropic Marin's kit, IMO it is the best on the market, easy to read and precise.
Whichever is easist for you to use and it sounds like Salifert is the winner. When you have finished these kits, you may want to try Tropic Marin's kit, IMO it is the best on the market, easy to read and precise.
Mick, you are 100% correct. I did the test again and waited over a minute at 24 drops. Guess what?? It turned blue. 360 for Sea Test and 350 for Salifert. Close enough for government work. Man you know your sh*t. I saw some of your other replies to posts and you seem to be right on the mark. Thanks again dude! BTW, I will give the Tropic Marin a try when these are dead. Have a nice holiday if we don't cross posts again...
Dan
Dan
You're welcome
I've done that test about a bazillion times so I've learned all the tricks, however Matt informed me this evening that there is one other trick. Supposedly the reason you get that muddy result is because the kit is being 'confused' by high levels of Magnesium, Strontium and other similar ions. If you cut your sample by 50% (I think that little test vial is 5 ml, so use 2.5 ml) and top it off with RO/DI and run the test and multiply the number of drops by 2 you will get a more obvious result.
MickAv8r,
I thank for your many informative posts but...
<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote
Do you know this for certain or are you just quessing?
This site: http://www.lars-sebralla.de/index2.html has many interesting analysis about different aquarium products and they clearly got different results for SeaTest and Salifert Ca tests.
Their analysis page: http://www.lars-sebralla.de/manalysen.html
Results for SeaTest and Salifert:
SeaTest error -60 to -7 mg/L
Salifert error +2 mg/L
Naturally you must take into consideration the operator error but if these tests were identical the operator error would on average be same.
BTW, like you said, Tropic Marin is quite accurate:
Tropic Marin error +11 mg/L
[ December 08, 2001: Message edited by: tatuvaaj ]</p>
I thank for your many informative posts but...
<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote
Do you know this for certain or are you just quessing?
This site: http://www.lars-sebralla.de/index2.html has many interesting analysis about different aquarium products and they clearly got different results for SeaTest and Salifert Ca tests.
Their analysis page: http://www.lars-sebralla.de/manalysen.html
Results for SeaTest and Salifert:
SeaTest error -60 to -7 mg/L
Salifert error +2 mg/L
Naturally you must take into consideration the operator error but if these tests were identical the operator error would on average be same.
BTW, like you said, Tropic Marin is quite accurate:
Tropic Marin error +11 mg/L
[ December 08, 2001: Message edited by: tatuvaaj ]</p>
<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr>Originally posted by tatuvaaj:
<strong>Do you know this for certain or are you just quessing?</strong><hr></blockquote>
Strong speculation.
Here are the reagents side by side:
As you can see they are very similar, 3 reagents, #2 being a purple powder in each instance.
However the similarity continues...
First translate the page into English - Goto Babel Fish at Altavista and put the following url with German to English selected: http://www.lars-sebralla.de/ma_ca_test.html
Now to surf amongst the different tests you click on each kit, check out the reagents and results of each kit. You will notice that they are all almost identical in reagents and color change.
Sera, JBL, Hagen, SeaTest, and Salifert all had pretty much identical reagents and tests. All the variance in results is mostly likely due to the sometimes muddy transition point than anything else.
If you notice the originator of this thread when he retested and added some precision to his method and gave the product time to react, his tests came out almost identical.
<strong>Do you know this for certain or are you just quessing?</strong><hr></blockquote>
Strong speculation.
Here are the reagents side by side:
As you can see they are very similar, 3 reagents, #2 being a purple powder in each instance.
However the similarity continues...
First translate the page into English - Goto Babel Fish at Altavista and put the following url with German to English selected: http://www.lars-sebralla.de/ma_ca_test.html
Now to surf amongst the different tests you click on each kit, check out the reagents and results of each kit. You will notice that they are all almost identical in reagents and color change.
Sera, JBL, Hagen, SeaTest, and Salifert all had pretty much identical reagents and tests. All the variance in results is mostly likely due to the sometimes muddy transition point than anything else.
If you notice the originator of this thread when he retested and added some precision to his method and gave the product time to react, his tests came out almost identical.
MickAv8r,
The colors shown for SeaTesT and Salifert really aren't even close. Salifert has a much more obvious color changes from bright pink to clear blue while SeaTesT has really murky colors and not so clear endpoint. I guess this is exactly the reason why people might get wildly different results with SeaTesT.
I must assume that pictures are telling the truth since Salifert colors are exactly the same as in real life (I have no experience about SeaTesT).
I still don't know if the SeaTesT reagents are made by Salifert but to me it is clear that the reagents are not the same.
Be sure to check this final page:
http://www.lars-sebralla.de/ma_ca_test06.html
If you read the first table it becomes clear that Salifert is by far most accurate hobbyist Ca test (Salifert results 395-410 mg/L and SeaTesT 330-405 mg/L). I think that two test kits couldn't be more different than that.
[ December 08, 2001: Message edited by: tatuvaaj ]</p>
The colors shown for SeaTesT and Salifert really aren't even close. Salifert has a much more obvious color changes from bright pink to clear blue while SeaTesT has really murky colors and not so clear endpoint. I guess this is exactly the reason why people might get wildly different results with SeaTesT.
I must assume that pictures are telling the truth since Salifert colors are exactly the same as in real life (I have no experience about SeaTesT).
I still don't know if the SeaTesT reagents are made by Salifert but to me it is clear that the reagents are not the same.
Be sure to check this final page:
http://www.lars-sebralla.de/ma_ca_test06.html
If you read the first table it becomes clear that Salifert is by far most accurate hobbyist Ca test (Salifert results 395-410 mg/L and SeaTesT 330-405 mg/L). I think that two test kits couldn't be more different than that.
[ December 08, 2001: Message edited by: tatuvaaj ]</p>
<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr>Originally posted by tatuvaaj:
<strong>The colors shown for SeaTesT and Salifert really aren't even close. Salifert has a much more obvious color changes from bright pink to clear blue while SeaTesT has really murky colors and not so clear endpoint.</strong><hr></blockquote>
They didn't wait long enough IMO.
That said I will concede the reagents are not IDENTICAL. Salifert Reagent #1 is Sodium Hydroxide, and SeaTest's is Potassium Hydroxide. The dyes are essentially the same and use approximately the same volume. No idea what the chemical makeup of the titrant reagents are however the amount used for a given reading is identical. 0.9 ml of Salifert titrant = 460 ppm, and the same amount equals 31 drops or 465 ppm with Fastest.
The only difference in the tests that I can find is that the ones that have a muddy transition, require more time and patience however they yield identical results.
<strong>The colors shown for SeaTesT and Salifert really aren't even close. Salifert has a much more obvious color changes from bright pink to clear blue while SeaTesT has really murky colors and not so clear endpoint.</strong><hr></blockquote>
They didn't wait long enough IMO.
That said I will concede the reagents are not IDENTICAL. Salifert Reagent #1 is Sodium Hydroxide, and SeaTest's is Potassium Hydroxide. The dyes are essentially the same and use approximately the same volume. No idea what the chemical makeup of the titrant reagents are however the amount used for a given reading is identical. 0.9 ml of Salifert titrant = 460 ppm, and the same amount equals 31 drops or 465 ppm with Fastest.
The only difference in the tests that I can find is that the ones that have a muddy transition, require more time and patience however they yield identical results.
<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote
I have understood that the reagent #1's function is to precipitate Mg out of solution and if you know the Ca concentration you can measure Mg by doing the test without reg #1 and then subtracting the Ca from result. Is this correct?
Also, don't you think that titrant must be different since Salifert gives so quick and much more easier endpoint?
Anyways, as an answer to the original question: you should trust the Salifert test result.
Also, it is helpful to go beyond the endpoint when you first do a test you haven't used before so that you can be certain what the final color really should be.
Thank you for your comments.
OK, that would explain why they got so low results with SeaTesT. In your picture the color change is much more dramatic.
I have understood that the reagent #1's function is to precipitate Mg out of solution and if you know the Ca concentration you can measure Mg by doing the test without reg #1 and then subtracting the Ca from result. Is this correct?
Also, don't you think that titrant must be different since Salifert gives so quick and much more easier endpoint?
Anyways, as an answer to the original question: you should trust the Salifert test result.
Also, it is helpful to go beyond the endpoint when you first do a test you haven't used before so that you can be certain what the final color really should be.
Thank you for your comments.
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