The OP is only holding hanna to their own standards, they claim an accuracy of 0.02, hanna has also stated that residue in the packet will not affect the results.
If you are claiming a margin of error of 0.07 is acceptable, what lvl would you think is unacceptable? 0.1? At such lvls it would almost be pointless running a test.
In my experience it's pointless to chase in a range from.03-.12 for any acro system. You aren't going to see a change in color or growth.
I'd be willing to bet that any of the P04 meters regardless of brand aren't going to give accurate/consistency levels better than a Hanna.
Hanna isn't testing 500 marine systems and giving you those levels of accuracy. People are woefully underestimating the dynamics of a reef tank..........there is variability that can't be accounted for in those tests.
They are giving you those numbers based on known lab levels of P04. It may just be a liquid calibration/comparison.
I have also mentioned other variables that can come into play when a person is doing the test.
You are comparing a handful of tests.....................the statistical sample is waaaay too small.
It's a $65 hobby grade tester, not some lab grade piece of equipment.
The OP hasn't compared it to other Po4 tests that claim the same accuracy. I have used Elos low level P04 test kits and they were comparable.
I have sent out ICP tests and it's reading was similar to the Hannah which I tested the day I filled the vials. I don't know what ICP company's testing protocol is.
Chasing P04 numbers is dumb in a range from .02-.10, it's only going to get you into trouble. It's way more important to look at the corals daily instead of focusing on minutia of some reef grade piece of test equipment.
The only time I make adjustments is when P04 was zero or above .20 and continue to show signs of rising. Zero is when I see corals change for the bad, shutdown and less alk consumption. Pushing above .30 growth slows down...........growth= color from a visual perspective.
I suggested testing fresh mixed saltwater to see if that may garner different results as you are eliminating quite a few variables............so far "crickets". I've done this numerous times and always get zero, but I have never done it 5 or more times in a row so that may offer some other perspective.
I can go on and on about this but it's probably going to be pointless, so I'm done with responding here...... I stated my points. opinions, experience.............If you don't like it that's fine.
If you want something different, look into the Elos low level kit.
The Expert Line Elos Aqua Test PO4- High Resolution Phosphate Test Kit is designed for the aquarist looking for a PO4 test kit that is both very easy to read and accurate at a very low range. For most the standard Prima Line Elos Aqua Test PO4 kit is more than sufficient, as it provides a low...
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