Do You Trust The Hanna Phosphate/Phosphorus Checkers?

[Sleeping Giant]

Everything in my tank is doing good, i have high phosphorus 74 ppb (0.227 ppm), I trust the checkers.

 

[Potatohead]

Firstly because they're still closed, and second because they don't measure phosphates in my gallery. That's something we would send to water quality to get tested, and I can't send my personal tank samples to water quality testing. Not every week or as often as I'd like to test.

The checkers are toys compared to real testing equipment. But unless a hobbyist wants to spends five figures on proper equipment, we are working with what's available.

I wasn't personally attacking you. The most important thing with the checker (aside from clean vials) is time span. You need five minutes between reagent activation and test result measurement. This is why the mixing period is two minutes, plus the built-in countdown timer.

I too was having problems with the checker, but once I bought new vials, keep them very clean and follow the five minute procedure, the results are very consistent.

 

[Sleeping Giant]

I

The checkers are toys compared to real testing equipment. But unless a hobbyist wants to spends five figures on proper equipment, we are working with what's available.

I wasn't personally attacking you. The most important thing with the checker (aside from clean vials) is time span. You need five minutes between reagent activation and test result measurement. This is why the mixing period is two minutes, plus the built-in countdown timer.

I too was having problems with the checker, but once I bought new vials, keep them very clean and follow the five minute procedure, the results are very consistent.

I too wasn't attacking, just asking why you weren't checking it at the aquarium business you work at.

 

[ScottB]

I too find the Hanna Checker to be the most annoying kit I use, but there really is no choice for low nutrient measurement.

Over time, I have managed to keep test results pretty consistent. What helped:
a) replace cuvettes immediately if they get a scratch
b) nitrile gloves
c) electrostatic wiping cloth
d) 2 vials, two minute mix time
e) extra care with reagent loading; every spec goes into the cuvette
f) store vials filled with RODI

All that said, my Hanna consistently reads .02 to .04 high relative to ICP.

 

[Albertan22]

I do trust my checker. I have typically received test results around what I expected. The levels fluctuate but typically trend in the directions I expect. I have also struggled getting my nutrients up except for me it’s the reverse, I have some phosphate but no nitrate. I feed pellets via auto feeder and have just come to the conclusion I need more fish. I wouldn’t be surprised if you’re just not dosing enough. I believe that phosphate and nitrate are consumed together with a higher rate of nitrate being consumed than phosphate. With more available free nitrate in the system the phosphate is the limiting factor in consumption. I bet if you increased your phosphate dose even more you’d see the nitrates drop on their own.

 

[Potatohead]

I also find when dosing phosphate, there is a delay in test results. It's not like alkalinity where you can dose, test ten minutes later and see your dose. The delay is usually a few days and probably longer if your rock and sand is still absorbing some or all of it. The same also in reverse, you can lower your dose and not see it for a few days.

 

[blstravler]

The checkers are toys compared to real testing equipment. But unless a hobbyist wants to spends five figures on proper equipment, we are working with what's available.

I wasn't personally attacking you. The most important thing with the checker (aside from clean vials) is time span. You need five minutes between reagent activation and test result measurement. This is why the mixing period is two minutes, plus the built-in countdown timer.

I too was having problems with the checker, but once I bought new vials, keep them very clean and follow the five minute procedure, the results are very consistent.

How do you clean your vials? - something I always struggle with.

 

[Potatohead]

How do you clean your vials? - something I always struggle with.

Well, I don't really. I rinse them with RO when they're done and then store them upside down, so if there are any deposits left over it ends up on the threaded part where the checker isn't reading. I might citric acid bath them every few months at best.

Maybe a year ago I was so concerned with the performance of my meter I bought new vials and the standard solution. The solution is supposed to be 100 and I tested three times and got 94,96,94, which is good enough for me. Since then with new vials doing the above, it has been very consistent.

 

[Potatohead]

I will also go over my testing method, not saying this is the right way, but it works for me very well.

1) I only use one vial
2) Wipe outside of vial with lint free cloth. Do not touch it with your fingers again from this point forward.
3) Use a syringe to put 10ml water into the vial. Do not dip it in the tank
4) Cut open a reagent pack like the attached pictures show (not my pics). Knock any remaining reagent out of the edges and corners.
5) Prepare a separate three minute timer
6) Go through the C1 routine. Do not touch the vial with your fingers, hold the lid only. Put the 10ml mark facing directly forward
7) as soon as C2 starts flashing, start your separate timer.
8) Pour in the reagent, making sure to check corners in the pack and add any remaining. If you have to hold the vial, use the cloth. This usually takes me 20-30 seconds.
9) Flip vial upwards and downwards for additional ~1:50 minutes holding the lid. I do not shake.
10) Wipe vial with cloth and put back into checker, make sure 10ml mark is facing same way as before.
11) Hold button for three minute timer. There is usually about 15-25 seconds remaining on the separate timer for me when doing so.

This works for me and is very consistent

 

[Albertan22]

I do pretty much the same routine, except I do touch the vial when I flip it for my 1:50. I put one finger on the lid and one on the bottom, but I fully wipe the vial again before putting it into the unit. I’ll miss the time maybe 1 out of 5 times and it’s usually because I get caught messing around trying to tap out some reagent power that stuck to the sides or deal with a bubble.

 

[Lasse]

I too find the Hanna Checker to be the most annoying kit I use, but there really is no choice for low nutrient measurement.

Over time, I have managed to keep test results pretty consistent. What helped:
a) replace cuvettes immediately if they get a scratch
b) nitrile gloves
c) electrostatic wiping cloth
d) 2 vials, two minute mix time
e) extra care with reagent loading; every spec goes into the cuvette
f) store vials filled with RODI

All that said, my Hanna consistently reads .02 to .04 high relative to ICP.

My HI774 always around 0.08 ppm above my ICP and test with Red Sea Pro Phosphate test. Knowing that - I can use it - just take away 0.08 ppm. But it nearly cost me my reef before I understand that. Precision can be bad in some checkers - IMO - and the repeatability is not better. The HI774 have ± 0.02 as accuracy on the paper. I always use two vials - one zero and one sample. I check that both show 0.00 and keep one as zero. Put in reagents in the sample vial and do as it should be done (2 minute shaking - 3 minutes waiting). after this - I take the zero and do the test procedure to the C2 is in the window. Change tube to the sample and a short press (reading directly without the 3 min) - note. New zeroing with the zero sample - C2 - change to sample vial - short press - read. Doing this for at least 10 times - here is my last readings

0.18, 0.17, 0.18, 0.19, 0.19, 0.16, 0.19, 0.19, 0.17 and 0.19 - and this was a good reading!

Sincerely Lasse

 

[anth]

I do trust mine
I sometimes used to compare it to salifert results (not really an accurate comparison but did read closely the same)
Also my icp tests have confirmed it twice
Error margin 0.005 or something tike that

 

[Sallstrom]

I've been testing with Hanna Checkers at work for more then five years, and my strategy is to take a test the same day as we send in ICP tests to Triton Lab. Then compare that specific Hanna to the Triton result. After doing that many times(we run many tanks and have tested at Triton since 2015, so I've had plenty of times to try this out) I get an idea of how that Hanna is compared to Triton. Usually the one I'm using now is about 0,02 lower then Triton PO4. Earlier Hanna I've used showed 0,03-0,04 lower than Triton. So this way I guesstimate my results when meassuring PO4 myself.
I find Hanna LR to be pretty good in precision. Me and Hanna ULR on the other hand didn't get along So I stick to the Hanna PO4 low range.

If getting zero in the test, I look at the corals. There's often one coral species in a tank that starts to look unhappy before the others when phosphate is too low. If that coral looks well, I'm happy with zero(and feed some extra.. ).

From what I've seen and tested, if using two different Hanna Checkers, you might get two different results. So you can't really compare one with another if you don't "calibrate" them in some way. And the result vary depending on who is doing them. My coworkers usually gets higher results then me somehow.

Here are three PO4 results from three tanks, from last week when I sent ICP tests to Triton.
Tank 1 - Hanna LR 0,02 - Triton 0,03
Tank 2 - Hanna LR 0,05 - Triton 0,03 (my coworker did this Hanna test. He usually gets a bit higher then me)
Tank 3 - Hanna LR 0,05 - Triton 0,04

So this time 0,02 lower on Hanna didn't exactly match, so now I know that. I'm happy with the results anyway

My procedure is to fill two vials, after rinsing them with tank water one time first. One vial for meassuring, one for mixing.
Mix for 2 minutes, then wipe the one without reagens and do the C1. Then eampty that and with a pipett fill it with the mixed sample and do the C2 (hold the button and wait 3 minutes). So I use the same vial for C1 and C2, but mix in the other. Works for me.

 

[Mortie31]

I use both flasks for the test, one with tank water for C1, and the other tank water and powder, I mix the powder for 1.5 minutes, then put flask 1 in tester (c1) then it says add c2, my mix is done and ready right away...then hold for my 3 minute timer.

This isn’t the correct way to test With a hanna checker, I’d advise reading the manual, testing correctly then seeing where you are before you do anything else..

 

[Lasse]

This isn’t the correct way to test With a hanna checker, I’d advise reading the manual, testing correctly then seeing where you are before you do anything else..

i´m sorry to say - if you follow the manual - it just a lottery when you analyse low levels. The one I use have a written accuracy of ± 0.02 ppm PO4 (HI774), HI713 have ±0.04 ppm and the HI736 have ± 5ppb P (around 0.015 ppm PO4)

It means that if I analyse a sample with the true value of 0.04 ppm PO4 - HI774 will show (if it a perfect meter with a perfect diode) from 0.02 to 0.06 ppm -> HI713 0 - 0.08 ppm and HI736 0.02 - 0.06 ppm.

I use both vials. First I do a double check. Filling both vials with sample - Put in my zero into the meter and follow the instruction to C2. Change vial and put in my sample vial - short press of C" (it will analyse direct without the 3 minutes). If I get 0.00 - I know that both vials are clean an pass together. Important that they are placed exactly the same way.

In my sample tube - I mix the reagent according to instructions for two minutes. Clear up all bubbles. Put the zero vial into the meter and when I reach C2 - shift vial to the sample vial (with the mixed reagent) long press and a 3 minutes colouring period starts. Read the result and print it down. Now I start with my zero sample and follow to C2. change the vials and do a short press - read and note. I do this till I have 10 readings. Take the average of these readings as my result.

If you try this - you will have some surprises - I promise

Sincerely Lasse

 

[chipmunkofdoom2]

After the replies to this thread, I decided to attempt to check the accuracy of my HI736. Here's the process I followed.

1. Create a phosphate solution with Na3PO4 (trisodium phosphate). Na3PO4 is 58% phosphate by weight. I added 7.12 grams to one gallon of deionized water. This produces a solution with a concentration of roughly 1,090 ppm phosphate.

2. Fill a 5 gallon bucket with fresh artificial seawater. Add a small pump for circulation

3. Test the seawater in the bucket and record result for baseline reading.

4. Dose 0.87 mL of the PO4 solution to the seawater. This should increase measurable phosphate to 0.05 ppm over baseline. Test and record result.

5. Dose 0.87 mL of the PO4 solution to the seawater. This should increase measurable phosphate to 0.10 ppm over baseline. Test and record result.

6. Dose 2.6 mL of the PO4 solution to the seawater. This should increase measurable phosphate to 0.25 ppm over baseline. Test and record result

7. Dose 4.34 mL of the PO4 solution to the seawater. This should increase measurable phosphate to 0.50 ppm over baseline. Test and record result.

Notes:
- I would have liked to scale the test up more so that measurement accounted for less possible error, but I didn't have enough equipment to scale the test any further. This scale should have been adequate to answer the question at hand.
- The Checker's battery was replaced before the tests
- Procedure from the Checker instructions were followed exactly with all tests.
- One cuvette was used for both the C1 and the C2 test.
- The cuvette was inspected for any scratches or blemishes before the tests began. There were none.
- Before the tests, the vial was cleaned with vinegar then deionized water.
- Between each test, the vial was rinsed with tap water, then deionized water.
- The cuvette was wiped with a clean, dry cloth before it was placed in the Checker.
- During step C2, the vial was mixed for exactly two minutes as measured by a timer.
- The reagent packets were opened and prepared before the test began to ensure that there was ample time to allow two full minutes of mixing
- The Na3PO4 used was a 99.9% pure food-grade supplement
- The scale used to measure the Na3PO4 has a maximum capacity of 500g and reads in increments of 0.01g
- The container used for the Na3PO4 solution in step 1 was a clean 1 gallon plastic jug that previously contained distilled water. It was rinsed with tap water, then deionized water
- The Na3PO4 solution in step one was mixed for several minutes and allowed to settle for a few hours.
- The seawater used in this test was Instant Ocean mixed to 52.5 mS (about 35 ppt). It had been mixing for just over 2 days prior to the tests.
- The 5 gallon bucket from step 2 was rinsed thoroughly with distilled water
- The circulation pump from step 2 was soaked in deionized water overnight
- The doses from steps 4 through 7 were dosed with a clean, new 1 mL syringe
- To determine the dose of Na3PO4 solution to add, I used the following equation. I refactored a common dosing calculation to allow me to solve for the amount of solution to add:

TV = tank volume
TC = tank concentration
SV = volume of solution dosed
SC = solution concentration
Dc = desired concentration

Results

The results were not good. Here is the expected and actual results in PPM:

Test	Expected Reading (PPM)	Actual Reading (PPM)
1​	0​	0​
2​	0.05​	0.006​
3​	0.1​	0​
4​	0.25​	0.077​
5​	0.5​	0.15​

And in PPB (actual measured results):

Test	Expected Reading (PPB)	Actual Reading (PPB)
1​	0​	0​
2​	16​	2​
3​	33​	0​
4​	82​	25​
5​	163​	49​

Charts:

Needless to say I'm pretty disappointed. I'm going to post in the Chemistry forum and get Randy's advice before emailing Hanna and asking them what the problem is. It's possible I messed up something in my testing procedure, but I doubt it.

 

[TexasReefer82]

Here's some of my own data that I've taken wrt the HI736 checker that I though was germane to this discussion.

I also test my water at the same time as I send out samples to ICP (ATI). In past months the phosphate values of ICP and Hanna ULR checker have been pretty close - considering the LOD and accuracy of the checker. But the last couple tests have begun to deviate to a degree beyond that which is explicable by gauge error. The table below summarizes my phosphate results.

My initial thought was that a chemical is accumulating in the tank (perhaps due to my heavy coral feeding) that is interfering with the spectraphotometric measurement of the Hanna. Due to a high Tin reading on July 13 I performed a single 80% water change which lowered the Tin value by exactly 80% on Aug 4. However, the phosphate level changed very little according to my Hanna (understood that CaCO3 sorbs PO4 but an 80% WC should still make a big difference). The ICP tests showed a dramatic decrease in phosphate as would be expected (I think 0.1 is dramatic, haha).

The deviation between hanna and ICP appears to be getting worse.

To those of you who replaced the glass cuvettes and saw improvement... do you think that would help here?