Hanna Phosphorus checker

[Merv49]

I have a question about running the Hanna Checker Phosphorus test:

How many times do you run the test with the same sample?

I ran the test and the 1st result was 17, then I decided to run it a couple more time just to see. I have 2 vials(one with sample and one with tank water) and just kept rerunning the test for a few times.

Here are the results

1. 17
2. 7
3. 5
4. 4
5. 7

Which number should I use? Or do a avg of them all?

I have the ULR standard and it reads the same every time. I suggest you get a standard if you want to verify accuracy. After that any variation might be assigned to testing procedure accuracy.

 

[MnFish1]

I have the ULR standard and it reads the same every time. I suggest you get a standard if you want to verify accuracy. After that any variation might be assigned to testing procedure accuracy.

You can only test one time. Per hanna. Not sure what your asking though. Why would you want to test a sample more than one time??

Ps testing a standard multiple
times is much different than testing a sample with reagent

 

[fishbox]

I had a bad vial one time that was driving me crazy ;Wacky
I finally figured out that it was that one vial ;Wideyed

So, I went outside and threw it as far away as I could and it felt, really good ;Woot ;Woot

Just curious how you determined that it was the vile itself that was bad? And what was wrong with it?

 

[Forsaken77]

I think what people are missing is that you can do the 3 minute built-in timer or press for an immediate reading.

So if you do the 3 minute built-in timer and it displays the reading, you can then immediately press the button again for another instant reading. The instant reading, like 5 seconds after your 3 minute reading, is always usually different. You can keep pressing the instant reading one after another and keep getting different results. What explains the difference in a reading taken at 3 mins, then 3.05 mins, then 3.10 mins?

The reading given at the 3 minute countdown should not be different then if you press for an instant reading on the same sample (with original calibration) just a few seconds after the 3 minute reading. But it is. So you guys are saying the sample degrades in a few seconds?

I'm not talking about waiting another minute or so. I'm talking about doing an instant reading immediately after you get the results from the 3 minute countdown.

 

[Chac317]

I’ve gotten readings of 0 the last 5 times I’ve tested, which I know is incorrect. Very frustrating.

 

[Dr RBG]

Would it help to use this?

HI736-11

Phosphorus Ultra Low Range Checker® HC Calibration Check Set
$12.00

 

[fishbox]

Good thread. I've been doing the timing right but I've been using one vile to zero out and another for the test solution to avoid the 2min time out. I also didn't know that it's recommended to orient the vile in the tester the same each time.

 

[sghera64]

I think what people are missing is that you can do the 3 minute built-in timer or press for an immediate reading.

So if you do the 3 minute built-in timer and it displays the reading, you can then immediately press the button again for another instant reading. The instant reading, like 5 seconds after your 3 minute reading, is always usually different. You can keep pressing the instant reading one after another and keep getting different results. What explains the difference in a reading taken at 3 mins, then 3.05 mins, then 3.10 mins?

The reading given at the 3 minute countdown should not be different then if you press for an instant reading on the same sample (with original calibration) just a few seconds after the 3 minute reading. But it is. So you guys are saying the sample degrades in a few seconds?

I'm not talking about waiting another minute or so. I'm talking about doing an instant reading immediately after you get the results from the 3 minute countdown.

I did not know you could do that (repeat pressing the button after C2 and get readings each time without re-zeroing). I’ll have to try that.

So, are the different number you at at 3.00, 3.05, 3.10 minutes going up slightly each time? Or are some higher and some lower than the previous reading?

What I would expect (assuming you can do this without re-zeroing each time), is that each immediate re-reading would be slightly higher and lower with an overall increasing trend. The reason I speculate this is that the instrument has some repeatibility error. It’s not perfect. This can probably be demonstrated by anyone with one of the Hanna phosphate standards. I’m guessing the Checker does not give the exact same reading each time.

I think the reading will trend upward between minutes 3 and 5 according to what MnFish1 reported from Hanna. This is because the color development begins when the reagent is mixed in the solution and continues for 5 minutes. Then a decomposition reaction begins and repeat readings will begin to trend down.

 

[Forsaken77]

I did not know you could do that (repeat pressing the button after C2 and get readings each time without re-zeroing). I’ll have to try that.

So, are the different number you at at 3.00, 3.05, 3.10 minutes going up slightly each time? Or are some higher and some lower than the previous reading?
wasat I would expect (assuming you can do this without re-zeroing each time), is that each immediate re-reading would be slightly higher and lower with an overall increasing trend. The reason I speculate this is that the instrument has some repeatibility error. It’s not perfect. This can probably be demonstrated by anyone with one of the Hanna phosphate standards. I’m guessing the Checker does not give the exact same reading each time.

I think the reading will trend upward between minutes 3 and 5 according to what MnFish1 reported from Hanna. This is because the color development begins when the reagent is mixed in the solution and continues for 5 minutes. Then a decomposition reaction begins and repeat readings will begin to trend down.

I don't remember which way it went or if there was a trend. I believe the readings were lower than the first one, but not positive. I just know it was a different reading and that the instructions state that you don't need to use the 3 minute built-in timer, you can just wait 3 mins and press for an instant reading. So I waited with the built-in timer, got the results, then immediately pressed the button again for the instant reading and it was different every time. This is the ULR unit.

 

[MnFish1]

I think what people are missing is that you can do the 3 minute built-in timer or press for an immediate reading.

So if you do the 3 minute built-in timer and it displays the reading, you can then immediately press the button again for another instant reading. The instant reading, like 5 seconds after your 3 minute reading, is always usually different. You can keep pressing the instant reading one after another and keep getting different results. What explains the difference in a reading taken at 3 mins, then 3.05 mins, then 3.10 mins?

The reading given at the 3 minute countdown should not be different then if you press for an instant reading on the same sample (with original calibration) just a few seconds after the 3 minute reading. But it is. So you guys are saying the sample degrades in a few seconds?

I'm not talking about waiting another minute or so. I'm talking about doing an instant reading immediately after you get the results from the 3 minute countdown.

The difference is that you cant do that - and have it be accurate. No offense - read the instructions. If not - call Hanna and ask them - probably it is partially re-zeroing the meter. The test is designed to be read at 5 minutes. Why are you asking here - just call the technical support and ask them - then let us know - again - not trying to be offensive - but - how would anyone here know how the chip in the reader works - or the answer to your question - which would be similar to:

I do the test - with 2 vials - then I set the test vial in the sun for 30 seconds - at noon. I re-zero with the vial - and the results are sometimes the same and sometimes they are different - why would that be>??

 

[MnFish1]

I did not know you could do that (repeat pressing the button after C2 and get readings each time without re-zeroing). I’ll have to try that.

So, are the different number you at at 3.00, 3.05, 3.10 minutes going up slightly each time? Or are some higher and some lower than the previous reading?

What I would expect (assuming you can do this without re-zeroing each time), is that each immediate re-reading would be slightly higher and lower with an overall increasing trend. The reason I speculate this is that the instrument has some repeatibility error. It’s not perfect. This can probably be demonstrated by anyone with one of the Hanna phosphate standards. I’m guessing the Checker does not give the exact same reading each time.

I think the reading will trend upward between minutes 3 and 5 according to what MnFish1 reported from Hanna. This is because the color development begins when the reagent is mixed in the solution and continues for 5 minutes. Then a decomposition reaction begins and repeat readings will begin to trend down.

According to Hanna you cannot do that.... Again - why keep reinventing the wheel here - Read the instructions - follow them - and do no more no less.

 

[fishbox]

So what are those readings then if not an instant reading? And before I'm told to read the manual or call Hanna, I'm just sharing my curiosity [emoji5]

 

[MnFish1]

So what are those readings then if not an instant reading? And before I'm told to read the manual or call Hanna, I'm just sharing my curiosity [emoji5]

I know - appreciated - but how would anyone here know - I already posted that I called hanna and repeated measurements are not valid... so. maybe you should call them and ask because I guarantee you - no one here will know 'why' they would be different. It must have something to do with the way they designed the test.

 

[MnFish1]

Here is the number - when the operator answers - ask for technical support; Phone: (800) 426-6287 • (401) 765-7500

 

[fishbox]

It just doesn't make sense that the results would be so much different in a 5 sec time frame. And there's very valid reasons for us to share our questions on the forum even if we intend to contact them.

 

[MnFish1]

It just doesn't make sense that the results would be so much different in a 5 sec time frame. And there's very valid reasons for us to share our questions on the forum even if we intend to contact them.

No there isn't a valid reason (and again im not trying to be a jerk). They sell a product - they provide instructions. There is no way anyone here can answer your questions - unless they work for that company. why philosophize on why something 'might be' when you can call and ask your question?

 

[Acuario]

To add my personal experience here, I broke a glass cuvette by dropping it. Bought a new cuvette set, and the results were different with the new cuvette than the old one that hadn't broke. I use the Hanna glass cleaner and cloth before each test and after shaking to keep the glass as clean as possible. Replacing the cuvettes once in a while is probably a good idea too.

 

[Forsaken77]

According to Hanna you cannot do that.... Again - why keep reinventing the wheel here - Read the instructions - follow them - and do no more no less.

Not trying to be offensive? If you have to say that then you know you are. I read the instructions. Would you like me to print them for you? According to the instructions the 3 minute built-in timer is optional. You also get an instant reading AFTER it was already zeroed out and you can wait 3 mins on your own. I stated that in the first post.

I'm not contacting Hanna because, frankly, I'm not losing sleep over it. I was responding to the thread, not to you. The OP was asking about different readings. My post was another relevant method that's available for use on the unit that gives different readings.

After it's zeroed out, and wants C2, you can use the built-in timer or wait 3 mins and tap the button for the reading instead of holding it down, per the INSTRUCTIONS.

After holding it down and waiting, it gives a reading. If you then TAP the button after that reading, it gives it's instant reading as if you waited 3 mins and pressed the button yourself. That reading already accounts for it being zeroed out.

But thanks for the input Mr Hanna, but nowhere in your instructions does it say you cannot do that. It's simply using 1 option after another. We call it double checking. No offense.

 

[fishbox]

With all due respect man you got to quit saying that no one in these forums can possibly answer that question unless they work there. There's thousands of members on this forum and there is a chance that someone has already made this phone call with that exact question. I mean hell we wouldn't have an equipment forum if it wasn't for asking questions like this and we as end-users wouldn't be modifying our equipment to better our hobby if it weren't for questions being asked on the Forum

 

[Forsaken77]

No there isn't a valid reason (and again im not trying to be a jerk). They sell a product - they provide instructions. There is no way anyone here can answer your questions - unless they work for that company. why philosophize on why something 'might be' when you can call and ask your question?

It's called a FORUM for people to discuss things. For example, inaccuracies in the equipment. We don't have to have a concrete reason WHY it does it, we're just sharing our experiences. Again, no offense, but maybe you should read the instructions on what a forum is.