ICP inaccurate?

Tphill · May 18, 2018

Just received my second ICP test results today. I have a couple issues with the results, which have me questioning the accuracy of the entire test. First, my PO4 results. On the first test, I did home tests at the same time I collected ICP samples. My Hanna checker gave me a PO4 reading of .021 and the ICP result was .01989612. I can live with that, it's reasonable. Now, on the second test, my Hanna checker gave me a PO4 of .028, tested at the same time the ICP samples were collected, and the ICP result was 2.237. That is a difference, and an increase, that seams incorrect.
Next issue. On the first ICP test, Mg result was 1243, while I tested it at 1290 with Salifert. Triton recommended I dose a total of 1442.62ml of their additive over a 7 day period. I only put in a full carton, 1000ml over the 7 day period. On the 8th day I collected the samples and sent the second test off. The results are 1234, with recommended dosing of 1544.26ml over 7 days. My Salifert test was 1440.
Anyone have any opinions or similar results to this? Did I just get a bad reading on the ICP test, and a bad batch of Mg from Triton? I'm going do my testing again tomorrow, but nothing seems wrong in my tank, especially not wrong enough to make me believe my PO4 is really 2.237. I believe I'll send a test off to ATI to see what they say.

Dogtown · May 30, 2018

Did you ever find out what the issue was?

Tphill · May 30, 2018

No, but Hanna still says .03, I did add more Mg, BRS this time. I can only guess maybe a small bit of food or something got in the sample, and over the 7 or so days between collection and testing, turned into phosphate.

Dogtown · May 31, 2018

You are probably right. Please do post how your next ICP test comes out.

I just mailed off my own ICP test for the first time yesterday so I'm curious what I will learn.