Contradictory Calcium Tests

I have a Salifert Calcium test kit and a Seachem Calcium test kit. The Salifert kit consistently (tested both daily for the last month) reads about 65 ppm higher than the Seachem. The Seachem kit came with a water sample to check for test accuracy and it reads at what it says it should. However, I still find myself wondering which test kit is truly accurate.

If it was just a small difference I wouldn't be worried so much but 65 ppm is huge. Anybody have similar results with these two different products? Is there something the Salifert kit might be detecting that would make it show a higher ppm and the Seachem kit doesn't check for it?

 

I would go with the Seachem, Salifert has had some quality issues, plus you confirmed against a test solution.

Seachem was formed by a hobbyist who was also a chemist, and is still run by hobbyists who are chemists.

 

Im a Seachem fan in terms of products myself so I feel the above advice is sound

what about getting a 3rd test done at the LFS ( providing that is they are not using any of the kits your using)
that way you would then have some verfication as to the reliability of the test kit your using

Steve

 

I have been going by the Seachem results, although mostly because they gave the lower calcium levels and I'd rather have high calcium than low. I use all Seachem products myself, but ever since I got a ridiculously bad batch of Seachem Reef Salt I have been wary of their marine products. I also have heard that different things show up on different brands of tests (i.e. borate alkalinity, etc.) so I was wondering if possibly the Saliferts readings were taking something I hadn't thought of into account.

Good idea on taking a sample to the lfs, I think I might do that this weekend.

Edit: I forgot to add that sometimes I am a bit suspicious of Seachem products because they seem to be built to get you to buy more of their other products. Low calcium reading=buy more Reef Complete, ya know? I don't get that feeling with Salifert.