Even higher quality companies such as Hanna and others have poor batches time to time. Unless they test their batches often and routinely, there's little way to ensure the accuracy.
They generally do when customers complain, that's about it and simply refund or replace. Who knows if they do or not test their batches often?
If they did, they'd say so to add value and marketing to their line. I would if I made test kits. :idea:
It would be foolish business wise not to tell folks this if they did it.
Testing is a reference science and as such, you need to test the kit at least once and if it sits over time for long periods(6 or more months). Bio science or not, the no# of replicates is still the same, the issue is likelyhood, Bio, manufacturing etc does not matter.
I'm highly skeptical of my data and want to be able to justify the results if asked and to make sure I did not over look anything.
That is why I test after all:idea:
Not everyone is going to though.
We all know that.
To be sure, to be able to offer the methods that show the test kit protocol is accurate, not to rely on company promises or beliefs or assumptions, I do things that way.
I think offering a test comparison like yours is great, but as you say, more needs to done there.
We did a similar test in the club about 10 years ago and have used mostly Hach and Lamotte ever since.
I've gone to lab spects the last 4 years which I calibrate every time I run test.
I generally will freeze the test samples and thaw for testing all at once as it's much faster to do test that way.
I will test 20 samples at a time and know they are all accurately measured.
Even our scales are calibrated by us for weights.
How far does a hobby need to go?
Well, a little calibration is good for most interested in narrow control for NO3 and PO4.
General wide ranges, Seachem is a decent company and I know Greg well enough and have discussed the issue with him several times over the years.
They are the only company that gives you a ref NO3 solution also
As far as PO4, it's non toxic to aquatic life, 100ppm ought not to have any adverse effect on any critter.
Regards,
Tom Barr
Is the PO4 at 10ppm toxic? It's non toxic even at 100ppm, to every aquatic form of life I know of. I've not seen any studies on toxicity because...well, it's non toxic for the most part over a very high range.