Kessil

Anybody using API test kits?

Ok, ran the Salifert and API against the standard.

API reads about .5 meq/L high.
Salifert reads about .1 meq/L low.

The .1 difference for Salifert could be due to inaccuracy of the weighing. The API definately is off though.

Thinking about remaking the standard by weighing 10x the amount of Na2CO3*H2O, making 100ml of solution, then taking 10ml of that to make the 2L of test standard.
 
[quote author=Thales link=topic=3011.msg34639#msg34639 date=1203649495]
From what the lab people at the aquarium tell me, you just want it to be just changed but stable, not bright yellow. :D
[/quote]

Yep, that's how I've always been taught to do titrations. But the API instructions say otherwise.

Similar situtation to Seachem tests. They actually give you a color sample to match, and they want you to go past to intermediate colors until you get to the first bright blue.

If you run Seachem Calcium that way, their reference standard tests properly and water test numbers match what you get from Salifert.
 
[quote author=Mr. Ugly link=topic=3011.msg34664#msg34664 date=1203666738]Yep, that's how I've always been taught to do titrations. But the API instructions say otherwise.[/quote]

Anyway, my modified API method gives precise and accurate results, so I'll stick with that.

I posted that method on the RC Chem forum, but nobody seems interested. Even though they're all asking about what test to use, and how to test, blah blah blah :D
 
[quote author=Thales link=topic=3011.msg34632#msg34632 date=1203644125]
I can't wait to see your results with the standard. If you drop some off on my doorstep on your way to work, I'll try it with my Elos kits. :D[/quote]

*ding* *dong*

*knock* *knock* *knock*

:D
 
Ok, made a 2nd batch of the 3.6 meq/L standard.

The electronic balance read down only to .01 grams. And also I was paranoid that the sodium carbonate monohydrate might have picked up additional moisture from the air.

I made some anhydrous Na2CO3 and weighed out 10x the amount required for a 2 liter batch.

3.6 X 50.04 X 106/100 x 2 x 10 = 3819mg = 3.82g

I used a 100ml volumetric flask to make up 100ml of stock solution

I used a 10ml volumetric pipette to take a sample.

I made that into the standard in a 2000ml volumetric flask.

Going to recheck the test kits against this version of the standard. Should be darn close if not the same.
 
Ok, this standard reads exactly 3.6meq/L using Salifert as well as by my modified API method.

I'll relabel the previous batch as 3.5meq/L standard :D
 
So that means that API used according to their directions reads .6 meq/L high.

That would be 1.68 dKH.

And since they go a drop at a time, API will misread at least 1 and up to 2 dKH high if you use their method.

Really sucky, hehe.
 
[quote author=Thales link=topic=3011.msg34632#msg34632 date=1203644125]
I can't wait to see your results with the standard. If you drop some off on my doorstep on your way to work, I'll try it with my Elos kits. :D[/quote]

Looks like the standard I left for you should read 3.5 meq/L or 9.8 dKH.

How's it look with the Elos?
 
[quote author=Mr. Ugly link=topic=3011.msg34683#msg34683 date=1203698104]
[quote author=Thales link=topic=3011.msg34632#msg34632 date=1203644125]
I can't wait to see your results with the standard. If you drop some off on my doorstep on your way to work, I'll try it with my Elos kits. :D[/quote]

*ding* *dong*

*knock* *knock* *knock*

:D
[/quote]

:D

3.5 standard tests to 10dkh or 3.57 with my Elos. Pretty on, since I only tested to the 1 dkh not .5. :D
 
[quote author=Mr. Ugly link=topic=3011.msg32492#msg32492 date=1202828384]
Just got some for the first time.

Reading way high for me.

Claims that a fresh batch of RC salt reads 5meq/L alk.

Grrrr....

http://www.reefcentral.com/forums/showthread.php?s=&threadid=1318165
[/quote]

Interesting story on API tests. Since I set up my tank my nitrate has read 20 before and after water changes. My pH also read 8.4 all along. So yesterday I took a sample to my LFS and he tested it with his kit. He showed my nitrate at 0 and pH at 8. Took another sample to a friends house to use his kit. Same reading as the LFS. So my conclusion is that my API test is bogus. Really makes me mistrust any test they offer.
 
Well, the 3 API's I have are from the same batch and read the same as each other. It's just that they read high and don't have good resolution if you go by their instructions.

I'm pretty happy with the modified API method. Plus I can recheck the API and other kits against the alk reference standard now.
 
[quote author=Mr. Ugly link=topic=3011.msg34631#msg34631 date=1203643039]
If anybody wants some alk standard lmk. That is if I don't get some crazy numbers from it.
Same for the 35ppt refractometer standard I made a while back.
[/quote]



Hey Norm, any chance I can take you up on those standards? Also, any chance you have a Ca standard? Unfortunately, I no longer have access to an analytical balance & volumetric glassware :(
 
I'll bring some to the meeting.

Thinking about making up a bunch of small bottles to sell if people are interested.

Maybe for a donation that gets split with BAR or something.

Haven't made Ca or Mg standards. Checking in on that :D
 
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