Hanna ULR Phosphate Tester - Have I been using it wrong this entire time?

[JCOLE]

I dosed Vibrant for 1.5 months and stopped almost 3 weeks ago. Corals were doing great up until I started Vibrant. Since the start I lost a Birdsnest colony to tissue necrosis and other corals have suffered including a purple stylo which I created a thread about that today as well. I have had Cyano for the last couple months and after I stopped dosing a couple weeks ago it got substantially worse. I dosed Chemiclean on Monday and all Cyano was gone within 48 hours. I did a water change yesterday and one tonight.

My corals just dont seem right including my purple stylo which has lost its color in its tips and my birdsnest polyps are not full like they used to be.

So before my water change tonight I tested No3 and PO4. The way I test PO4 with the Hanna is with 2 cuvettes. Both filled with 10ml of tank water. I pour the reagent into one cuvette, set a timer and shake for 2 minutes. After two minutes I clean both cuvettes with a microfiber cloth and put in the first cuvette. Then I put in the second cuvette afterwards for my reading. My reading has been pretty consistent and usually around .05ppm.

During testing tonight I tested differently than I have always done. I always start with Red Sea NO3 because after mixing it has a 9 minute wait time. During the wait I jump into the PO4 testing. I had to test NO3 twice tonight which caused me to let the PO4 reagent sit in my cuvette(I have never done this before) for around 3 minutes while I mixed my second NO3 test. I went back to the PO4 cuvette after sitting for 3 minutes and shook it for 2 minutes like I normally do. I could see the blue color and knew there was phosphates. I tested and the Hanna read .39!!

I assumed this was an error so I retested PO4. This time I poured the reagent in and shook right away for 2 minutes like I normally do and performed the test. This time it tested at .04. Significantly lower and around where I normally read at.

So I started thinking and decided to test for a 3rd time. This time I replicated what I did the first time. I poured the reagent in and let it sit at the bottom of the cuvette for 3 minutes. Then I shook for 2 minutes. Tested and again it was around .82!!

So, is that the correct way to test? If my phosphates are truly that high then that would probably explain why my corals look the way they do.

First test - not my normal way

Second test - My normal way

3rd test - Just like first test. Let it sit in cuvette for 3 minutes then shook for 2 minutes

 

[Thaxxx]

The way the directions say.
You don't let it sit for 3 minutes before you shake it.

 

[Homebrewer]

Agree, just follow directions exactly. Don’t let the granules sit before you shake.

FWIW, I like to zero with the exact same sample in the exact same cuvette to decrease on the number of variables (i.e. one less cuvette, one less sample). So what I’m saying is I use one cuvette for the whole process. Nothing sits around.

 

[infinite0180]

The test is designed to be ran at the 5 minute mark after adding the reagent. Blank it out with water. Add reagent. Its 2 minutes of shaking/mixing then into the checker. Long press the button and it counts down 3 minutes. Thats a total of 5 minutes...

 

[Kyl]

You're supposed to use the same cuvette for the zero and sample, as @Homebrewer has noted. Also, always run them in the same position. I like to use the 10ml marking facing foward as a reference point. This means there will be no variations in the glass of the cuvette that can potentially cause reading variations.

As for the test itself:

Zero out sample
Empty packet into cuvette as much as possible, quickly. Shake for the 2 minute timer, insert and hold to start the 3 minute count down. The roughly ~5 minutes of exposure to the reagent brings out the best state for it to be tested, it is time sensitive.

 

[Larry L]

 

[Homebrewer]

You're supposed to use the same cuvette for the zero and sample, as @Homebrewer has noted. Also, always run them in the same position. I like to use the 10ml marking facing foward as a reference point. This means there will be no variations in the glass of the cuvette that can potentially cause reading variations.

As for the test itself:

Zero out sample
Empty packet into cuvette as much as possible, quickly. Shake for the 2 minute timer, insert and hold to start the 3 minute count down. The roughly ~5 minutes of exposure to the reagent brings out the best state for it to be tested, it is time sensitive.

Yes, good point about the position. Another variable removed.

 

[JCOLE]

I have tested it the normal way hundreds of times with same results. Also, whether I use one or two cuvettes it doesnt matter. I get the same results. I use 2 cuvettes so I am not in a race against the clock before the tester shuts down after the 3 minute shut down feature. What is the difference If I shake for 2 minutes immediately then sit for 3 minutes or let sit for 3 minutes and shake for 2 minutes?

Just curious as the reagent is mixed with sample water for the same 5 minutes of time. One way gives much different readings though.

 

[moreef]

Problem I have is the dang thing shuts off before Im ready. When I finally get the sample ready and push and hold button it goes back to C1. Is there anything wrong with using 2 curvetes?

 

[JCOLE]

Problem I have is the dang thing shuts off before Im ready. When I finally get the sample ready and push and hold button it goes back to C1. Is there anything wrong with using 2 curvetes?

That is why I use two cuvettes as well and I also believe that is why two come with the kit.

 

[moreef]

That is why I use two cuvettes as well and I also believe that is why two come with the kit.

They sure make it look easy in the video lol. Now if they would find better container for powder of better yet liquid reagent then using one would be easy.

 

[Homebrewer]

I have tested it the normal way hundreds of times with same results. Also, whether I use one or two cuvettes it doesnt matter. I get the same results. I use 2 cuvettes so I am not in a race against the clock before the tester shuts down after the 3 minute shut down feature. What is the difference If I shake for 2 minutes immediately then sit for 3 minutes or let sit for 3 minutes and shake for 2 minutes?

Just curious as the reagent is mixed with sample water for the same 5 minutes of time. One way gives much different readings though.

I’m not sure why there is a difference, I can only speculate that the reagents are time-sensitive in some way (as evidenced (partially) by the need to wait 3 minutes before the final measurement is take ). If you’re just genuinely curious, it may be worth reaching out to Hanna to find out. I spent enough time in labs back in the day, if I thought about this some more I could probably figure this out.

However, good laboratory practice dictates that you change only one variable at a time. What I think is important here is that when you changed a variable (test methodology), you saw a difference, but when you didn’t, you saw no difference. Therefore I would humbly suggest sticking to the directions or the normal way, and you can be assured that your results will be consistent test-to-test, with the only variable being your sampled water at each testing.

 

[Kyl]

The instrument shuts down after 3 minutes of non-use. This reflects the proper window of time needed for the chemical reaction to take place for accurate analysis. Prior to turning on your meter, fill the cuvette with 10 mL of unreacted sample and replace the cap. Cut open one packet of HI 713-25 reagent and set aside. Turn the meter on by pressing the button. All segments will be displayed. When the display shows “Add”, “C.1” with “Press” blinking, the meter is ready. Place the cuvette with 10ml of unreacted sample into the meter and close the meter’s cap. Press the button. When the display shows “Add”, “C.2” with “Press” blinking the meter is zeroed. Remove the cuvette from the meter and unscrew the cap. Add the content of one packet of HI 713-25 reagent. Replace the cap and shake gently for 2 minutes until the powder is completely dissolved. Place the cuvette back into the meter.Press and hold the button until the timer is displayed on the LCD (the display will show the countdown prior to the measurement) or, alternatively, wait for 3 minutes and press the button.

The time out between C1 and C2 should be 3 minutes, coupled with 2 minutes of shaking, this leaves the user with 1 minute to pour the powder reagent into the cuvette. It is recommended to have the powder sachet open and ready to pour prior to starting the test.

Can you re-affirm that using a single cuvette for both portions of the test is the correct method? I was told not to use both as glass variances between cuvettes can impact the test.

Yes this is correct.

Also Place Cuvettes in the Same Position Every Time
Why: When using a Checker, it's important that the length of the optical path is always the same to ensure consistent and accurate readings every time.

http://blog.hannainst.com/checker-best-practices

 

[GoldeneyeRet]

It is important to use just one cuvette per test. It is also important to clean and wipe the cuvette very well. Failure to follow these steps results in inconsistent readings.

To save on time, open and prepare the reagent packet first. After zeroing you have one minute to pour the powder in and replace the cap, which is way more than enough, even for a klutz like me.

 

[Homebrewer]

That is why I use two cuvettes as well and I also believe that is why two come with the kit.

With respect to my comments on limiting variables, I agree with other postings, including the one quoted from Hanna, which says to use the same one.

 

[moreef]

It is important to use just one cuvette per test. It is also important to clean and wipe the cuvette very well. Failure to follow these steps results in inconsistent readings.

To save on time, open and prepare the reagent packet first. After zeroing you have one minute to pour the powder in and replace the cap, which is way more than enough, even for a klutz like me.

So the total time before it shuts off is 3mins? This brings me to another point what the heck do they have this thing turn off after 3mins lol. My battery isnt going to drain in 5 or 7 mins if that is how long it takes. Seems hanna overlooked some things that would have made testing much easier.

 

[MnFish1]

Read the instructions and do it that way,...... Everything else it / will be inaccurate.

 

[JCOLE]

I completely understand the logic behind all of this and yes I also have an instructions card as well. I am just curious as how letting it sit for 3 minutes gives me a reading of .82 and not letting it sit gives me a reading of .04.

I will reach out to Hanna and see what they have to say.

 

[MnFish1]

So the total time before it shuts off is 3mins? This brings me to another point what the heck do they have this thing turn off after 3mins lol. My battery isnt going to drain in 5 or 7 mins if that is how long it takes. Seems hanna overlooked some things that would have made testing much easier.

If you do the test according to the instructions it takes less than 3 minutes - so there is nothing wrong here - if you are taking longer, you are not following the instructions. There are multiple threads on this - with people using various methods - all of which end up causing abnormal results. Follow the instructions exactly and stop second guessing the test - or at least use a different method /test to verify/refut it - dont try to do it by changing the instructions of the test itself, IMHO - and because I've read 90% of these threads and called hanna tech support

 

[GoldeneyeRet]

I dont think hanna overlooked anything. The test is simple as can be.