Phosphate checker usability problem?

[pscott99]

Originally Posted by notclear

I also do that, but I think it will give reasonable accurate reading.

Me also. It gives me lots of time to make sure they are clean and have no bubbles. I always do the test over again right away (same two vials not new water or reagent ) and find it usually drops by some small amount which makes me happy with the first result.

If someone wants to waste a reagent do the test with one vial and a second test with two vials. I doubt they would differ significantly. I am now on my second set of replacement reagent and have never wasted a pack. If I could get my PO4 near zero and get rid of algae I wouldn't need to test so often !!

[wyattroa]

I don't know, I can test two samples in a row and get .10 reading on one sample and .03 reading on another sample.. Almost every time my two reading do not come out the same.

[iwishtofish]

Just used my new phosphate Checker for the first time, after watching a friend use it earlier in the day. First go, I got 0.18; second go, I got 0.34.

After cleaning the cuvettes thoroughly with RO/DI water and then sample water (did this first time), using a piece of paper to catch and bottle nearly 100% of the reagent, and making sure the outsides of the cuvettes were completely free of any saltwater residue and fingerprints, I got a reading of 0.07.

PITA, but I'm happy enough with the results (providing they are correct, haha). My assumption is that getting every bit of the powder into the cuvette is crucial for a good test. It is, as others have said, extremely annoying with the current packaging.

Anyhow, now I guess I need to lower that number...

One quick question, though. Should the bottom of the meniscus be right at the line on the cuvette? How critical is that?

[xp964]

Originally Posted by iwishtofish

Just used my new phosphate Checker for the first time, after watching a friend use it earlier in the day. First go, I got 0.18; second go, I got 0.34.

After cleaning the cuvettes thoroughly with RO/DI water and then sample water (did this first time), using a piece of paper to catch and bottle nearly 100% of the reagent, and making sure the outsides of the cuvettes were completely free of any saltwater residue and fingerprints, I got a reading of 0.07.

PITA, but I'm happy enough with the results (providing they are correct, haha). My assumption is that getting every bit of the powder into the cuvette is crucial for a good test. It is, as others have said, extremely annoying with the current packaging.

Anyhow, now I guess I need to lower that number...

One quick question, though. Should the bottom of the meniscus be right at the line on the cuvette? How critical is that?

Hello iwishtofish,

Yes, the bottom of the meniscus should be right at the line of the cuvette. Accuracy is key!

Thanks,
Hanna

[LISound]

Originally Posted by xp964

Hello iwishtofish,

Yes, the bottom of the meniscus should be right at the line of the cuvette. Accuracy is key!

Thanks,
Hanna

Sorry, where should the water level be in regards to the line?

[xp964]

Originally Posted by LISound

Sorry, where should the water level be in regards to the line?

The meniscus should touch the 10 mL line of the cuvette. See the attached picture.

[iwishtofish]

Originally Posted by xp964

Hello iwishtofish,

Yes, the bottom of the meniscus should be right at the line of the cuvette. Accuracy is key!

Thanks,
Hanna

Ok, thanks!

Originally Posted by LISound

Sorry, where should the water level be in regards to the line?

The meniscus is that bowl-shaped curve that the top of the water inside the test vial makes.

[igadget56]

This youtube video from Hanna is for the calcium checker. It says the meniscus should be at the top of the line. What is the correct way.

http://www.youtube.com/watch?v=LGjpicL6hTk

[xp964]

Originally Posted by igadget56

This youtube video from Hanna is for the calcium checker. It says the meniscus should be at the top of the line. What is the correct way.

http://www.youtube.com/watch?v=LGjpicL6hTk

As seen in the picture attached above, and in the YouTube video, the meniscus should touch the top of the 10 mL line on the cuvette.

[drukkosz]

I would still like to know the answer to those questions:

1. If the powder aren't completely dissolved? Lower or higher reading?
2. If there are a few micro bubbles at the top of the cuvette? Lower or higher reading?
3. If I can not all of the power to the cuvette? Lower or higher reading?

I dont know why they are ignoring it??

I bought phosphate checker last week and it was broken straight from the box! have new one and now occasionally after counting down from 3 minutes is stops on 36 or 14 seconds. I have to start everything again and another reagent wasted!
Not going to even say anything how annoying those little packages are!
Everybody is complaining about it so why they wont change it? It cant be that difficult!!

[xp964]

Hi Drukkosz,
Did you post those questions on another thread? I'm not seeing where those came up before and want to make sure the answers get posted with them.

1. If the powder still isn't completely dissolved by the end of the 1 minute 45 second shaking, it will not affect the reading as long as you see that it is dissolved when you remove the vial after the three minute countdown and reading. If there is still undissolved powder at that point, it is likely that you will get a false low, but it is impossible to quantify.
2. Micro bubbles at the TOP should not affect the reading. If there are micro bubbles suspended in the middle or clinging to the glass in the middle, it will affect the reading in ways that are unpredictable.
3. If you do not get all the powder into the vial you will get a false low. Again, this is impossible to quantify.

I'm sorry that you have had difficulties with your Checker, and I understand that you are unhappy. It sounds like your current Checker is not functioning correctly still; have you contacted our Tech Support department regarding this? They may be able to determine the issue and repair or replace if necessary.

Unfortunately, it is incredibly difficult, time consuming, and expensive to change production lines. We would have to change not only the phosphate packaging, but the packaging for all our dozens of powder reagents, which would in turn affect the outer packaging of the reagent and the meters they go with. This must be done in coordination with all 32 Hannas, many of which have multiple branches.
Hanna USA is not in charge of manufacturing. We have notified Hanna Inc of our desire of a packaging change, but we have not as yet been notified of any modifications.

Thank you,
Hanna USA

[drukkosz]

no i didnt post those questions. dzhuo asked that 3 or 4 times in this thread

Thanks for answering it.
So are you saying that both of my checkers are broken?? Wow where is quality control??

I guess i will have to call them, but my point is that if something is brand new is should work! why i have to go through all those headaches

[xp964]

I already answered him, back in January, on this thread.

Originally Posted by xp964

1. Won’t affect the reading as long as it’s mostly dissolved before starting the reaction count down – the reagent will dissolve the rest of the way in that two minute reaction. Unless you have relatively high phosphate levels (>1.0 mg/L), there won’t be enough phosphate in the sample to react with all the reagent anyway.

2. Micro bubbles at the top of the cuvette will have no effect on the reading. Only microbubbles in the center of the cuvette, where the light passes through, would have an effect on the reading. (Microbubbles in the path of the light would cause a false positive, as they would refract extra light.)

3. This would only have any effect if (a) there was a significant amount of reagent left in the packet (see our how-to video on how to get it all out, http://www.youtube.com/watch?v=8e_EO...layer_embedded) or (b) there were high levels of phosphate (> 1.0 mg/L) in the sample. (Either of these two scenarios would cause a false negative.)

Again, my apologies that you've had difficulties with your Checkers. If you'll contact Tech support, or PM me your contact information so that I may have them contact you, we will take care of you.

Thank you,
Hanna USA

[drukkosz]

thank you i appreciate your help, I will call them later today
sorry i guess i have missed your answers