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The 5ml syringe that comes with many Salifert kits, e.g.; PO4, K and O2, are not accurate. They deliver 10% more sample water than the nominal 5ml required by the test instructions. Obviously, this can skew results. I’ve always used increased/diluted approaches (which eliminates use of these syringes) to improve accuracy, so I didn’t notice until I did a quick GH test using one of these 5ml syringes. I then checked all of them and they are all the same. You can adjust by drawing sample water to what shows on the syringe as 4.5ml. The 2ml and 1ml syringes used in tests, such as the NO3 test, are accurate.

I questioned whether or not Salifert calibrated to the inaccurate syringes or to actual 5ml quantities. It appears that the actual 5ml quantity is used. However, I only confirmed this with their GH test kit (it was off). Is it meaningful? You will still be in the ballpark by drawing to the 5ml level on these syringes, but will be a little closer by either making the adjustment to 4.5ml with the syringe or using a different approach to ensuring 5ml sampling.

I still believe that Salifert tests, generally, are better quality than other reagent tests for certain parameters (NO3, PO4, K and TAN). So, I continue to recommend them, but on this adjusted basis.
 

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The 5ml syringe that comes with many Salifert kits, e.g.; PO4, K and O2, are not accurate. They deliver 10% more sample water than the nominal 5ml required by the test instructions. Obviously, this can skew results. I’ve always used increased/diluted approaches (which eliminates use of these syringes) to improve accuracy, so I didn’t notice until I did a quick GH test using one of these 5ml syringes. I then checked all of them and they are all the same. You can adjust by drawing sample water to what shows on the syringe as 4.5ml. The 2ml and 1ml syringes used in tests, such as the NO3 test, are accurate.

I questioned whether or not Salifert calibrated to the inaccurate syringes or to actual 5ml quantities. It appears that the actual 5ml quantity is used. However, I only confirmed this with their GH test kit (it was off). Is it meaningful? You will still be in the ballpark by drawing to the 5ml level on these syringes, but will be a little closer by either making the adjustment to 4.5ml with the syringe or using a different approach to ensuring 5ml sampling.

I still believe that Salifert tests, generally, are better quality than other reagent tests for certain parameters (NO3, PO4, K and TAN). So, I continue to recommend them, but on this adjusted basis.
This is rather disturbing info and especially so if happening on a grand scale.

Did you happen to contact and question Salifert about it?
 

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Discussion Starter · #3 ·
This is rather disturbing info and especially so if happening on a grand scale.

Did you happen to contact and question Salifert about it?
No. Last time I checked, Salifert not only had a nearly useless website, but there was no contact information. If you judged them by their website, you would think they didn't want to be in business.
 
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