Hanna Checker Phosphate ULR accuracy

[aus1230]

Not exactly what to think here or maybe this is normal so I apologize in advance. I know these checkers might have discrepancies but is this just a small one or a big difference?
Initial reading was 0.03
2nd reading was 0.2
3rd reading was 0.90 which seamed like a crazy discrepancy so I decided to test again
The 4th reading was 0
Is that normal to have those variations after doing back to back tests with new packets within minutes of each other?

The packets expire this December if that's worth anything?

 

[Reefer Matt]

Not exactly what to think here or maybe this is normal so I apologize in advance. I know these checkers might have discrepancies but is this just a small one or a big difference?
Initial reading was 0.03
2nd reading was 0.2
3rd reading was 0.90 which seamed like a crazy discrepancy so I decided to test again
The 4th reading was 0
Is that normal to have those variations after doing back to back tests with new packets within minutes of each other?

The packets expire this December if that's worth anything?

Might be a bad batch of reagent.

 

[gbroadbridge]

Not exactly what to think here or maybe this is normal so I apologize in advance. I know these checkers might have discrepancies but is this just a small one or a big difference?
Initial reading was 0.03
2nd reading was 0.2
3rd reading was 0.90 which seamed like a crazy discrepancy so I decided to test again
The 4th reading was 0
Is that normal to have those variations after doing back to back tests with new packets within minutes of each other?

The packets expire this December if that's worth anything?

The stated accuracy is +/- 0.03 ppm.

Wild variations like you are seeing are not normal.

Are you following exactly the same procedure each time?
Especially are you letting the reaction complete for 3 minutes by pressing and holding the button until the 3 minute timer starts?

Also make sure the battery is okay

 

[aus1230]

The stated accuracy is +/- 0.03 ppm.

Wild variations like you are seeing are not normal.

Are you following exactly the same procedure each time?
Especially are you letting the reaction complete for 3 minutes by pressing and holding the button until the 3 minute timer starts?

Also make sure the battery is okay

I for sure am even down to asking Siri to start my timer for shaking
And down to telling Siri to start my 3 minute timer so I can come check on it.
Is there a certain way to check the battery status to verify that it’s good?

 

[aus1230]

Might be a bad batch of reagent.

My thoughts exactly. I purchased this checker second hand and am now starting to question the packets that were given to me and possibly even the checker.

 

[gbroadbridge]

My thoughts exactly. I purchased this checker second hand and am now starting to question the packets that were given to me and possibly even the checker.

Expiry date on the reagents?

But even if that date is okay, if they've been left in damp areas or in the sun they could be bad.

In the absence of a voltmeter, best check for the battery is replace with a known good one.

 

[aus1230]

My thoughts exactly. I purchased this checker second hand and am now starting to question the packets that were given to me and possibly even the checker.

Expiry date on the reagents?

But even if that date is okay, if they've been left in damp areas or in the sun they could be bad.

In the absence of a voltmeter, best check for the battery is replace with a known good one.

The packages say 12/25. But I agree with what you said I cannot say with certain that they weren’t exposed to those elements since I bought them along with the used meter. I guess I’ll purchase some new ones tomorrow put in a new battery and test three samples and if it still happens I suppose I’ll get a new unit.

 

[Tangdora]

1) What are are you using to draw your sample
2) are you using the same vial for each test if so are you using rodi to clean out the sample or tap
3) were all 4 test drawn from the same spot

 

[Shirak]

That’s quite a difference! Did all 4 look similar in color? .03, 0 would be almost colorless and .9 dark blue.

 

[fushi]

Check for finger print smudges on the vial or bubbles on the walls of the vial. The Hanna uses a photocell and light to read the color, any changes in the clarity of the center of the vile will throw off the test.

 

[Shirak]

Check for finger print smudges on the vial or bubbles on the walls of the vial. The Hanna uses a photocell and light to read the color, any changes in the clarity of the center of the vile will throw off the test.

I would add that I use the same vial every time and I have a small mark at the top of the vial so I can orient it facing the same direction when putting it into the checker.

 

[fushi]

I would add that I use the same vial every time and I have a small mark at the top of the vial so I can orient it facing the same direction when putting it into the checker.

This too, I use the “10ml” label as my reference mark

 

[aus1230]

1) What are are you using to draw your sample
2) are you using the same vial for each test if so are you using rodi to clean out the sample or tap
3) were all 4 test drawn from the same spot

1. A syringe
2. I was using different vials all clean and dried prior to testing
3. Yes, I would say so. I usually grab water from the left side of my tank when I move my lid off just a little.

 

[aus1230]

That’s quite a difference! Did all 4 look similar in color? .03, 0 would be almost colorless and .9 dark blue.

If I’m being honest none of them had any color when finished. Would that mean the reagent then?

 

[aus1230]

That’s quite a difference! Did all 4 look similar in color? .03, 0 would be almost colorless and .9 dark blue.

The .9 definitely was not dark blue I would’ve noticed the change in color.

 

[aus1230]

Check for finger print smudges on the vial or bubbles on the walls of the vial. The Hanna uses a photocell and light to read the color, any changes in the clarity of the center of the vile will throw off the test.

I usually wipe down every vial before inserting since I’ve read there could be water droplets that can throw the test off.

 

[fushi]

I clean every vial with rubbing alcohol and a microfiber cloth, if you’re dunking the whole vial in the tank, be careful about water sitting underneath the cap, the Hannah readers are not water resistant.

Also, I found the biggest discrepancy to be little micro bubbles inside the vile, after my two minutes of shaking I slowly rock the bottle back-and-forth to clear up any bubbles inside.

 

[aus1230]

I clean every vial with rubbing alcohol and a microfiber cloth, if you’re dunking the whole vial in the tank, be careful about water sitting underneath the cap, the Hannah readers are not water resistant.

Also, I found the biggest discrepancy to be little micro bubbles inside the vile, after my two minutes of shaking I slowly rock the bottle back-and-forth to clear up any bubbles inside.

I’ll be purchasing some new reagents either way today and will be more diligent in checking for some of the recommendations above. If I still have big swings I guess it’s time for a new checker as this one is used and I have no idea how old it really is.

 

[fushi]

I clean every vial with rubbing alcohol and a microfiber cloth, if you’re dunking the whole vial in the tank, be careful about water sitting underneath the cap, the Hannah readers are not water resistant.

Also, I found the biggest discrepancy to be little micro bubbles inside the vile, after my two minutes of shaking I slowly rock the bottle back-and-forth to clear up any bubbles inside.

I’ll be purchasing some new reagents either way today and will be more diligent in checking for some of the recommendations above. If I still have big swings I guess it’s time for a new checker as this one is used and I have no idea how old it really is.

Hopefully, there’s an easy fix for you.

Some other things you might want to check are batteries and maybe wipe out the inside of the checker with a Q-tip to clean out any dust on the sensor.

 

[aus1230]

I clean every vial with rubbing alcohol and a microfiber cloth, if you’re dunking the whole vial in the tank, be careful about water sitting underneath the cap, the Hannah readers are not water resistant.

Also, I found the biggest discrepancy to be little micro bubbles inside the vile, after my two minutes of shaking I slowly rock the bottle back-and-forth to clear up any bubbles inside.

Would you take a look at Shirak’s comment? He made a comment about the .9 would have been a dark blue. It was in fact not blue when I pulled it out. Would that be a problem with the checker then?