Hannah Phosphate ULR Reliable??

[BrokenReefer]

Leading question:

Has anyone experienced a discrepancy between a Hannah checker and any other test kits? I checked with a Red Sea Phosphate Pro test against my Hannah Phosphate ULR just now and the ULR is reading .90 (flashing to indicate higher values); Red Sea test kit (following the high value directions) gave me .255.

Is there a calibration solution for the Hannah?

Am I possibly doing the testing wrong?

Open to suggestions.

 

[Uncle99]

Leading question:

Has anyone experienced a discrepancy between a Hannah checker and any other test kits? I checked with a Red Sea Phosphate Pro test against my Hannah Phosphate ULR just now and the ULR is reading .90 (flashing to indicate higher values); Red Sea test kit (following the high value directions) gave me .255.

Is there a calibration solution for the Hannah?

Am I possibly doing the testing wrong?

Open to suggestions.

I have never in 100,s of tests with the Hanna ever got a weird number. Best kit I ever used.

Nothing else ever worked for me for phosphate.

Did it work, then down the road gave that response, or new batch reagent…..? Anything like that?

 

[EricR]

My Hanna Phosphate ULR matched my LFS Milwaukee pretty closely the few times I compared on same water sample,,, so I trust mine (within reason).

 

[BrokenReefer]

I have never in 100,s of tests with the Hanna ever got a weird number. Best kit I ever used.

Nothing else ever worked for me for phosphate.

Did it work, then down the road gave that response, or new batch reagent…..? Anything like that?

I should have gotten the high range tester since I’ve been chasing a wicked nitrate/phosphate spike for the past month. All that’s to say I am not sure. The reagent is a really faint blue color, which visually at least, tells me the my PO4 is down.

Is it possible that the tester is dirty? My kids may have gotten their dirty little fingers on it, especially my 1.5 yr old son. The little monster is teething so he’s sheets chewing on his fingers

 

[BrokenReefer]

My Hanna Phosphate ULR matched my LFS Milwaukee pretty closely the few times I compared on same water sample,,, so I trust mine (within reason).

I plan on redoing the rest tonight after the kids are in bed and if it’s still wildly disparate, I was thinking of sending in for ICP. We have a full weekend of kid fall activities, so me trying to get to the LFS is slim.

 

[Idech]

Hanna Phosphate ULR can’t be use while dosing silicate because it gives false results. Are you dosing silicates ?

 

[BrokenReefer]

Hanna Phosphate ULR can’t be use while dosing silicate because it gives false results. Are you dosing silicates ?

I am not

 

[Idech]

I am not

Then it should be reliable. I’ve done ICP tests and they gave the almost same exact result as the Hanna phosphate ULR.

Maybe try some new reagents ?

 

[Miami Reef]

Hanna Phosphate ULR can’t be use while dosing silicate because it gives false results. Are you dosing silicates ?

That is not true. Where is your source?

Silicates need to be much over about 5ppm to give any minor rise.

Zero difference. (undetectable)
you have to dose a ton of Si to get a tiny positive interference in the PO4 test kit.

 

[Miami Reef]

Tip to @Jason mack who brought it up earlier in a dino thread.
I was skeptical, but it seems to be true, and in some cases, it might change how we choose to dose and test etc.

This is a combo of data from me and @Rick Mathew

Saltwater spiked with different levels of Silica was measured for PO4 with the Hanna ULR P meter.
What is plotted is the difference in the PO4 measured value from its original (zero SiO2) value.
That Rick's (red) and my (blue) data are so closely in agreement given different Si sources etc makes the effect look likely to be real.

Is this a big effect? Not really. Hanna's Low Range Si checker maxes out at 2.00ppm SiO2. I know of no reason why anyone would want more than 2ppm SiO2. There is no evidence of significant interference at or below that range. But it looks like the interference starts around 2ppm SiO2 and becomes significant compared to the uncertainty in the PO4 test by 4ppm SiO2.
The interference is known about, but may be understated...

info in the Standard Methods - PO4 by ascorbic acid...
"b. Interference: Arsenates react with the molybdate reagent to produce a blue color similar to that formed with phosphate. Concentrations as low as 0.1 mg As/L interfere with the phosphate determination. Hexavalent chromium and NO2 interfere to give results about 3% low at concentrations of 1 mg/L and 10 to 15% low at 10 mg/L. Sulfide (Na2S) and silicate do not interfere at concentrations of 1.0 and 10 mg/L."

I'm not sure why we are seeing interference at a lower range than we ought to, but it seems to be the case. @Dan_P pointed out this is not a hanna issue, it's underlying chemistry - and other test kits will probably not avoid it either.

Under what case could it matter? Jason earlier pointed out the fact that Si is dosed sometimes by those trying to encourage diatoms to compete with dinos, and many don't want to test for Si, or get a faulty kit. Then there are certainly some out there that are shooting for PO4 in the 0.05-0.10 range and may only have half or less of that if they are dosing Si without a reliable Si kit.

 

[EricR]

I plan on redoing the rest tonight after the kids are in bed and if it’s still wildly disparate, I was thinking of sending in for ICP. We have a full weekend of kid fall activities, so me trying to get to the LFS is slim.

I don't know that ICP is the best way to validate home checkers. I think it should be reasonably close but the resident chemistry expert posted the following before (although maybe in a slightly different context):
ICP measures organic and inorganic forms while the Hanna is just inorganic orthophosphate, but the difference is unlikely to be that large.

I know nothing about the Red Sea test but your results seem pretty far off between the too.
*I have had bad Hanna Nitrate reagent before (which Hanna replaced for free) so reagent issues could be one possibility, although I haven't experienced that with Hanna Phosphate ULR before

Just out of curiosity, have your two testers matched in the past,,, or is one brand new?
*defective units could be a possibility but not sure about the background here

 

[Idech]

That is not true. Where is your source?

Silicates need to be much over about 5ppm to give any minor rise.

Well, I’m sorry but it is true. My source is myself having to deal with dinos three times and having false results (0,9 ppm while ICP test showed 0,03 ppm). And when I decreased silicate levels, Hanna became reliable again.

There are countless comments about it on social media too. I’m far from the only one.

The other Hanna phosphate reader is fine though. It seems to be only with this particular one.

 

[BrokenReefer]

I don't know that ICP is the best way to validate home checkers. I think it should be reasonably close but the resident chemistry expert posted the following before (although maybe in a slightly different context):
ICP measures organic and inorganic forms while the Hanna is just inorganic orthophosphate, but the difference is unlikely to be that large.

I know nothing about the Red Sea test but your results seem pretty far off between the too.
*I have had bad Hanna Nitrate reagent before (which Hanna replaced for free) so reagent issues could be one possibility, although I haven't experienced that with Hanna Phosphate ULR before

Just out of curiosity, have your two testers matched in the past,,, or is one brand new?
*defective units could be a possibility but not sure about the background here

I can always get more Hannah Phosphate reagent, that’s not a problem. The Red Sea test kit is brand new, re-measured and it was a bit higher at .34, seemingly not alarming. I am perplexed but an easy solve is new reagent. That’s a quick fix.

 

[EricR]

I can always get more Hannah Phosphate reagent, that’s not a problem. The Red Sea test kit is brand new, re-measured and it was a bit higher at .34, seemingly not alarming. I am perplexed but an easy solve is new reagent. That’s a quick fix.

I was just mentioning possibilities obviously.
Reagent issue seems like a stretch but anything's possible. (As I mentioned, I did have bad Nitrate reagent before).
If you buy more anyway and find that was the issue, Hanna will replace the bad reagent for free. (If not, you just have extra so no problem there).

If it were me, I'd be leaning towards a 3rd test from LFS to just get a feel for which of your testers is WAY OFF at this point (assuming you're sure you didn't just botch one of your tests with a method/procedure error or something).

Anyway, good luck...

 

[BrokenReefer]

I was just mentioning possibilities obviously.
Reagent issue seems like a stretch but anything's possible. (As I mentioned, I did have bad Nitrate reagent before).
If you buy more anyway and find that was the issue, Hanna will replace the bad reagent for free. (If not, you just have extra so no problem there).

If it were me, I'd be leaning towards a 3rd test from LFS to just get a feel for which of your testers is WAY OFF at this point (assuming you're sure you didn't just botch one of your tests with a method/procedure error or something).

Anyway, good luck...

Thanks! I appreciate you providing your input.

 

[jda]

Anything that clouds the water can interfere with a photometric test. Using LC which puts a bit of a fog in the water can make hannah checkers off by a little bit.

Most people have dirty vials that have test kits all over the place.

You have to pick something. If your vials were clean with no drops on the outside, then the Hannah is as good as it gets, IMO. I use both vials, wipe them clean and then use the 3 minute countdown. Once it is done, I run them through again really quick and the second number nearly always is around the first number.

 

[JohnNYC8]

Leading question:

Has anyone experienced a discrepancy between a Hannah checker and any other test kits? I checked with a Red Sea Phosphate Pro test against my Hannah Phosphate ULR just now and the ULR is reading .90 (flashing to indicate higher values); Red Sea test kit (following the high value directions) gave me .255.

Is there a calibration solution for the Hannah?

Am I possibly doing the testing wrong?

Open to suggestions.

I've only done 2 ICP tests but they've both been in line with the readings I get from the Hannah ULR Phosphate checker.

 

[jda]

Depending on your ICP testing place, they are likely just doing acetic acide based colormetric tests to determine po4 too. Remember that plasma cannot detect compounds such as po4 and only elements. For all that we know, they could be using a Hannah too.

 

[BrokenReefer]

Anything that clouds the water can interfere with a photometric test. Using LC which puts a bit of a fog in the water can make hannah checkers off by a little bit.

Most people have dirty vials that have test kits all over the place.

You have to pick something. If your vials were clean with no drops on the outside, then the Hannah is as good as it gets, IMO. I use both vials, wipe them clean and then use the 3 minute countdown. Once it is done, I run them through again really quick and the second number nearly always is around the first number.

I went to the LFS today with some water in tow, 1.39ppm; the Red Sea seems off but it's also likely human error (I don't know if the size of the droplets matter to the efficacy of the test but I did lop off a bigger chunk of the tip than intended).
Now I know where I'm at and how much more work there is to be done.

 

[BeanAnimal]

I am pretty sure that I would trust water test results from an LFS over my own. Yes, it is another data point, but the blind faith that people have in LFS testing is questionable.