AquaPharm vs. SeaChem CA test results.

[Blade_Runner]

Here I go again with not trusting test results. My LFS guy showed up at my office last week to do his monthly gig. (With me being in and out of town a lot, my staff no longer lets me fly solo on that tank.) While using a brand new AquaPharm CA test kit he came up with a value of 520 on the tank! We both went WTF as it has been running pretty consistantly in the low 400s when ever I check it. (CA is tested 2x a month on that tank and is stable in that range.) So I took the kit home and ran it next to my SeaChem kit on my home tank over the weekend. I had my wife do it too just to take user error out of the equation. SeaChem = 425m 430w and AquaPharm = 500m 520w.
What is up with that? After getting strange/unreliable phosphate results last week, I'm beginning to doubt any test results. IMO, it just goes to show how difficult it is to get your chemistry where you really want it and be able to properly track it, especially if you change testing methodology. Oh, $.02 I'm trusting SeaChem more than AquaPharm for CA readings. The results for both tanks are in more of a "logical" range.

[m_lacom99]

I noticed a difference in CA tests also... I use Salifert wich reads 430, wich i trust, and my freind tried the haggen tests wich reads 380. A good way to overdose CA in a tank.... I never tried the seachem CA test cause i was told that the powder in the test gets hard over time... or something like that.

Marc.

[Blade_Runner]

There is a powder, but I have not had any problems with it clumping up. I'm simply careful to keep it dry and make sure the lid is tight. The part I like about the SeaChem is they use a graduated syringe to add the tintrate. They also use an accurate pipette to add the sample. I can get a good look on what was dispensed down to .1 to .2 ml. Each ml = 50 ppt. Ass-u-ming the reagents are good, the kit has a very professional quality feel to it and can be read down to 10ppt.

[Covey]

My money is on the seachem kit. The Salifert test is notorious for for giving high reading. I started out using the AP test but pefer the seachem test of the three Cal test mentioned.

[Blade_Runner]

I a dumb sh*t. I forgot the SeaChem had a bottle of reference solution at 380. I re-ran both kits. SeaChem came in at 360. AquaPharm came in at 440. Since my 5 year old insisted on helping, when I was doing the SeaChem test I'd say it's pretty close and within operator error at that point.

I'm sticking with SeaChem.

[RAVEN]

There was an article published on the accuracy of various CA test kits and it stated that they greatly vary in their accuracy by 50-100ppm or more. If I can find the link to the article I will post it.

[Blade_Runner]

Add that to almost useless Phosphate tests and we are really cooking.

At least I know my refractometer is reasonably accurate.

[Matt Rogers]

I always forget about the reference solution too.

I really like the Seachem CA kit as well. I put the powder in a small tupperware container to keep it from clumping. Prior to that, it clumped up from moisture but Seachem sent me another for free!

[Blade_Runner]

Everybody keeps talking about the clumping. It was a little clumped up when I first opened it so I shook it up pretty good to break them up. I've used about 1/2 of the 150 tests and still don't have any clumping. I open, scoop, immediately close the lid tightly, give it a couple of shakes for good measure and put it away. If it's consistantly testing within 20 ppt it's a keeper.

[Covey]

Above all else just don't store in the stand. Mine hasn't clumped.