The quest for the most accurate test kit.

[Liam]

I have been getting questionable calcium results with my test kits recently so i took a sample to Brendan at Skiptons for a cross reference and he tested my water at 400ppm with his Seachem kit.I tested the same sample with my Lamotte kit and with the undilute test stopped the test at 1200ppm before i ran out of titrant,then ran their diluted 12:1 test and came up with 495ppm.The undiluted test is innaccurate due to high levels of mineral salts in salt water according to Lamotte so you must use the diluted test.
So this leaves me with either 400 or 495 which is a considerable difference IMO and which one do i believe as both are reputable tests.
I am new to BRS but wondered if it has'nt already been done would it be an idea for a study at a meeting where we obtained a sample of known values and ran various tests with various brand kits and find out which ones are actually accurrate and which ones are just accurrate according to their manufacturers.Maybe we could even test some monitors especially the new calcium monitor.
Any thoughts???

 

[starrfish]

Test kits can become inaccurate over time as they age - regardless of the manufacturer. The problem is that the kit may sit on the shelf a long time before you even purchase it. One nice thing about the Seachem kits is that they come with a reference sample so you can test the titrant against the reference to see if it's still accurate. I had the same problem with a brand new Salifert calcium kit, so I went back to Seachem.

 

[Liam]

Surely the reference sample is the same age as the other test components?

 

[starrfish]

Good question...I'm not sure if the reference sample is impacted by age the same as the titrant.

 

[broadwave]

I vaguely remember a post where they did just that...test with different kits on teh same know solution on Reef Central.

Just do a search on it. Other wise go to the Reef Chemistry forum and ask Randy Folmes-Farley about it, he's a local guy and may have the answer for you.

 

[Liam]

Thanks Broadwave,could'nt find that exact post so i posted a thread for Randy .

 

[Shallowwaters]

FWIW
I realized my Salifert Ca test was off compared to my Seachem test. The Seachem tested fine with it's 400 ppm reference sample. When I tested the Seachem reference sample with Salifert, I found it was under counting the Ca by 100 ppm.

It has been 7 months since I bought my Salifert test.

 

[ScottM]

i have lamotte, Seachem and salifert. your welcome to test.