Problems with Hanna Phosphate and Phosphorus checkers

[ElmoC]

I have both these units and I have been getting very inconsistent results. I wanted to get something to compare the results against so I got a Salifert Phosphate checker. I ran 3 tests with Salifert and all 3 came out to zero. Since I have been running ROWAphos, that is what I was expecting. I then ran a test with the phosphate checker and got 0.04. That is within the +/- 0.04 ppm accuracy of the meter. I then ran a test using the phosphorus checker and got 0.15!

 

So who should I believe? How accurate is the Salifert test? There is not even a hint of blue in the results. But I am not sure about this test. The powder portion is the consistency of a dry powder snow. Is that how it is suppose to be?

[Arkayology]

Buy some calibration solution and see which one is most correct.

[tlombardo]

I think that with the phosphorus vs phosphate checkers they measure in different units?? IE ppm vs ppb. There also may be a conversion you need to do from the phosphorus checker to measure phosphATE which is what the other two are measuring. Unless you are already aware of this in which case I have been completely un helpful

[ElmoC]

I think that with the phosphorus vs phosphate checkers they measure in different units?? IE ppm vs ppb. There also may be a conversion you need to do from the phosphorus checker to measure phosphATE which is what the other two are measuring. Unless you are already aware of this in which case I have been completely un helpful

 

Thanks for at least trying. Yes, I am aware of the conversion (multiply by 0.003). The real problem is if I run 3 tests on the same water, I get 3 different results with at least one of them outside the accuracy range. With the phosphate test, there should be a number, or range of numbers, all three tests share that are within the accuracy of each test. That isn't happening. I'm getting really suspicious of the reagent quality because of this. I was hoping to find others who have had this issue and find what resolved it for them.

[tlombardo]

Thanks for at least trying. Yes, I am aware of the conversion (multiply by 0.003). The real problem is if I run 3 tests on the same water, I get 3 different results with at least one of them outside the accuracy range. With the phosphate test, there should be a number, or range of numbers, all three tests share that are within the accuracy of each test. That isn't happening. I'm getting really suspicious of the reagent quality because of this. I was hoping to find others who have had this issue and find what resolved it for them.

ha sorry! good luck finding the solution. I like Arkayology's idea if that sort of thing is available.

[ElmoC]

ha sorry! good luck finding the solution. I like Arkayology's idea if that sort of thing is available.

 

I was looking for some calibration fluid like they suggested, but wasn't having much luck. It's not as easy to find as the pH and salinity fluids, but I'm still looking.

[seabass]

http://www.championlighting.com/product.php?productid=36804&cat=0

 

As for accuracy. Have you run several consecutive tests to see if they consistently provide the same results? There could be anomalies which made one or more tests inaccurate (like bubbles in a sample, fingerprints on a vial, spilled reagent, reagent trapped in the package, etc).

 

It's a big task to ask a hobby test kit to accurately measure parts per billion. Plus, the results of my Hanna Phosphate Checker do tend to jump around a bit. I often pay more attention to the trend/average of tests over time.

 

[ElmoC]

I have ran several consecutive tests and get results all over the place. Ran 5 tests once and got readings from 0.00 all the way up to 0.19. With the accuracy of 0.04, some of those readings are flat out wrong. Which ones, I'm not sure.

 

I just came across that calibration set earlier. Do you know how much fluid is in each vial?

[seabass]

I'm not sure how they work, but I assume that you place the first vial in the Checker for the reference sample, then the second vial in for the test reading. Could be wrong (never used them before).

[tigrtraps]

Thanks for at least trying. Yes, I am aware of the conversion (multiply by 0.003). .

 

 

 

I'll ask it, are you just multiplying the ppb number by .003 or are you doing the math above that was just provided by seabass?

 

Edit: Nevermind, it's such a small difference in the final numbers that it doesn't really matter.

 

My Phosphorous checker is consistent, but I curse at that reagent packet every time I pour it in the vial.

[seabass]

... I curse at that reagent packet every time I pour it in the vial.

I know, right? Why can't they package it in the form of a tube instead? It would be so easy to just place the open end inside the vial and flick it a couple of times.

[ElmoC]

Or even better, a liquid reagent like the alkalinity checker uses.

[Mstefa1]

I have Salifert phosphate test kit and I only ever once received a reading of 0.03. Every other time it is 0.00. It's just not sensitive enough. Your welcome to have mine as I wrote it off as a waste of money. I do however love Salifert Ca and Alk tests.

 

I also have the Hanna phosphorous checker and am very happy with it. The results can be consistently reproduced if you give any thought to what you are doing. But I also run lab testing at work too so I'm used to doing things consistently.

 

Start out with only 1 vial. Make sure it is clean. Make sure you always discard old solution, rinse, and store it full with RODI water. This prevents staining or buildup on the glass that could influence the colorimeter.

 

Dump out the RODI, and rinse several times with aquarium water. Then fill to line. Make sure that there are no particulates in the vial.

 

Dry and clean the vial taking care to remove any finger prints. Put the vial into your meter and zero out. Note the orientation of the vial by paying attention what direction the printing on the vial is facing.

 

Using the same vial, put the reagent into the vial making sure that you got all of it in. Do not let your fingers touch the inside of the pouch or the reagent. Don't use a different vial as this could produce different results.

 

Continue to invert vial to dissolve the reagent. Don't shake aggressively because it will create air bubbles. Using a stopwatch (download an app) or using the timer feature on your microwave (I do my testing in the kitchen), pay attention to when your 3 minutes before auto shutoff expires. When you get close, stop shaking and continue by rotating in a spinning fashion to keep it moving while cleaning the vial with a cloth.

 

Put the vial into the meter making sure you install it in the same orientation and start the cycle.

 

After the cycle is completed, rinse and store the vial using the previous mentioned method.

 

Note: If you intend to do a recheck, prepare a new solution. If you retest the already tested solution you will NOT receive the same result because the reagent had a longer time to react.

 

Personally, I use the phosphorous checker and convert to phosphate. I find the results accurate, reproducible, and consistent with what I am expecting.

[ElmoC]

Other than storing with the RODI water in it, that is pretty much how I do the tests. Might try getting a few new vials and try it again storing the RODI water in them.

 

Do you know where I can get some phosphate test solution? I would like to try running the tests on water with a known level and see what type of readings I get. I saw that Hanna sells a check kit, but I would rather use a 3rd parties product just so I know it's not specifically geared to the checker.

Continue to invert vial to dissolve the reagent. Don't shake aggressively because it will create air bubbles. Using a stopwatch (download an app) or using the timer feature on your microwave (I do my testing in the kitchen), pay attention to when your 3 minutes before auto shutoff expires. When you get close, stop shaking and continue by rotating in a spinning fashion to keep it moving while cleaning the vial with a cloth.

 

On the time, are you mixing it for the nearly 3 minutes then putting it in the tester and then starting the 3 minute timer on it or after mixing, just doing a straight reading? I had read on procedure to put in the reagent and then start the 3 minute timer on the checker and start mixing. After 2 minutes, clean and replace the vial and then wait for the timer to run down.

[Mstefa1]

Other than storing with the RODI water in it, that is pretty much how I do the tests. Might try getting a few new vials and try it again storing the RODI water in them.

 

Do you know where I can get some phosphate test solution? I would like to try running the tests on water with a known level and see what type of readings I get. I saw that Hanna sells a check kit, but I would rather use a 3rd parties product just so I know it's not specifically geared to the checker.

 

Storing wet with RODI isn't exactly a procedure, just something I do. Additionally, there is another member on here that things along the same lines as I does the same. I don't know where you can get a phosphate calibration solution.

 

 

On the time, are you mixing it for the nearly 3 minutes then putting it in the tester and then starting the 3 minute timer on it or after mixing, just doing a straight reading? I had read on procedure to put in the reagent and then start the 3 minute timer on the checker and start mixing. After 2 minutes, clean and replace the vial and then wait for the timer to run down.

 

I'm mixing it for 2 minutes however it takes me almost 1 minute to get the reagent into the vial. The reason I my own timer is because during this step, the checker will auto shutoff after 3 minutes so you obviously don't want to wait too long here. Essentially, I follow all of the directions listed on the included card for my Phosphorous checker. It's just that I take a little more care in the preparation and storage.

[ElmoC]

I'm mixing it for 2 minutes however it takes me almost 1 minute to get the reagent into the vial. The reason I my own timer is because during this step, the checker will auto shutoff after 3 minutes so you obviously don't want to wait too long here. Essentially, I follow all of the directions listed on the included card for my Phosphorous checker. It's just that I take a little more care in the preparation and storage.

 

So is the total time between putting the reagent in the vial, mixing, and getting the results 3 minutes or 5?

[Mstefa1]

So is the total time between putting the reagent in the vial, mixing, and getting the results 3 minutes or 5?

 

If I recall, zero checker, then 3 minutes (1 minute to add reagent + 2 minutes to mix), then 2 minutes for it to test on it's own.

[ElmoC]

If I recall, zero checker, then 3 minutes (1 minute to add reagent + 2 minutes to mix), then 2 minutes for it to test on it's own.

 

I must be missing something because those times don't add up. Did you mean 3 minutes for it to test on it's own? That is how long the internal timer runs for. So it takes about 6 minutes total?

[Mstefa1]

I must be missing something because those times don't add up. Did you mean 3 minutes for it to test on it's own? That is how long the internal timer runs for. So it takes about 6 minutes total?

 

Ok, then 2 minutes for it to test on it's own. Been a few weeks since I've tested.

 

Your over thinking. Just follow the directions and take some care into making sure you do everything the same each time.

[jservedio]

The Salifert Phosphate test is garbage and is totally useless unless your phosphates are off the charts. The sensitivity is very low and it isn't a titration style test (like their Alkalinity). Just looking for nuisance algae is a better test for phosphate than the Salifert test...

 

The Hanna Phosphate checker is both incredibly accurate AND precise (whereas their Alk checker is very precise, but not totally accurate). When the Hanna Phosphate checker is compared with several thousand dollar lab spectrometers, it matches up with negligible error. This is by far Hanna's best checker and is the best $50 you will spend if you are trying to deal with problem phosphates.

 

Trust your Hanna Phosphate checker if you are following the directions - it is definitely correct. Ignore the Salifert Phosphate test - it is complete garbage.

 

* I have both and I LOVE all of Salifert's other test kits - I am not just bias against Salifert. In fact, besides Phosphate, I use Salifert kits for everything else - including Alkalinity which I use to double check my Hanna Alk Checker.

[ElmoC]

Trust your Hanna Phosphate checker if you are following the directions - it is definitely correct. Ignore the Salifert Phosphate test - it is complete garbage.

 

How can I possibly trust the Hanna when I do 5 tests, using the same procedure, and get results ranging from 0.00 to 0.19? Given the unit has a +/- 0.04 accuracy, one or more of those readings are wrong.

 

I am going to try getting some new reagents and run some more tests. If anything, I think that may be the real source of the problems.

[Rehype]

Hey elmo i had inconsistent results as well with the phosphorous checker in the past but i did change my method a bit which helped tremendously.

 

Ive always used two cuvettes..initially because the issue with the short timer but now since i like to recheck my results.

All cuvettes are wiped clean with a microfiber cloth prior to each test, each cuvette and cap is rinsed with tank water prior to testing. Care is taken to make sure all the powder agent is introduced into the cuvette. The instant re-tests are done using the second cuvette for the C1 standard sample. The one thing i do differently after having results similar to yours is after i mix the reagent for a full two minutes i let the C2 sample sit for 7 minutes before adding it to the checker.At which point it will still sit for the standard 3 minutes. So thats a total of 10 minutes before the C2 sample is read. In my experience that has helped with the variance in readings. My guess is the sample needs to settle longer before being read.

 

Heres a sample reading using the above method

 

Initial- 11ppb Immediate follow up tests-8,9,11,11,11 and after waiting nearly 30 minutes..15

[Mstefa1]

Hey elmo i had inconsistent results as well with the phosphorous checker in the past but i did change my method a bit which helped tremendously.

 

Ive always used two cuvettes..initially because the issue with the short timer but now since i like to recheck my results.

 

All cuvettes are wiped clean with a microfiber cloth prior to each test, each cuvette and cap is rinsed with tank water prior to testing. Care is taken to make sure all the powder agent is introduced into the cuvette. The instant re-tests are done using the second cuvette for the C1 standard sample. The one thing i do differently after having results similar to yours is after i mix the reagent for a full two minutes i let the C2 sample sit for 7 minutes before adding it to the checker.At which point it will still sit for the standard 3 minutes. So thats a total of 10 minutes before the C2 sample is read. In my experience that has helped with the variance in readings. My guess is the sample needs to settle longer before being read.

 

Heres a sample reading using the above method

 

Initial- 11ppb Immediate follow up tests-8,9,11,11,11 and after waiting nearly 30 minutes..15

 

 

So basically what your saying is your not following the directions?

 

I've read on RC from a rep that letting the sample sit reduces the accuracy of the test. Hence the reason for the 3 minute time limit. In my experience, a retest using the same reacted sample always reads a higher result.

 

The reason I use the same cuvette to zero out the meter and also run the test is because over time you could develop differences in the transparency of the glass due to staining or issues.

[Rehype]

So basically what your saying is your not following the directions?

 

I've read on RC from a rep that letting the sample sit reduces the accuracy of the test. Hence the reason for the 3 minute time limit. In my experience, a retest using the same reacted sample always reads a higher result.

 

The reason I use the same cuvette to zero out the meter and also run the test is because over time you could develop differences in the transparency of the glass due to staining or issues.

 

Well im basically saying is that IME following the directions consistently gave me inconsistent results. It could have just been my meter but the only way i got consistent results were with the method i mentioned above.

[jservedio]

How can I possibly trust the Hanna when I do 5 tests, using the same procedure, and get results ranging from 0.00 to 0.19? Given the unit has a +/- 0.04 accuracy, one or more of those readings are wrong.

 

I am going to try getting some new reagents and run some more tests. If anything, I think that may be the real source of the problems.

 

Either the procedure you are following is off or the reagents are bad. Even though the phosphate checker is listed as +/- 0.04 ppm, when tested against actual lab equipment, it is much, much more accurate.

 

Their alkalinity test is definitely +/- 5ppm (consistently at least), but the phosphate one is much, much better. The Salifert Phosphate test simply isn't sensitive enough to differentiate between 0.00 and 0.06ppm accurately or repeatably.

 

Edit: When you turn the meter on, calibrate it, and put the sample in with reagents - make sure the meter doesn't move at all and the light doesn't change at all - changes in light can effect the checkers. Use the same cuvette and clean it off between zeroing the unit and putting the reagent in (when you invert the cuvette, wipe it off afterwards). Any smudges will throw off the results since it is measuring light transmission and smudges mess that up significantly.