Hanna Phosphorus checker

[rtparty]

Dont understand whaat you mean - if you put in a mixed vial to begin with - the result will be zero when you do the test . (what do you mean by mixed vial)?

If you get a vial of water and reagent and then zero that, the machine will zero off whatever color that solution is.

The checker isn't looking for perfectly clear water when it zeroes

 

[Cory]

Exactly as rtparty said. The sample of water has a color. Usually from tannis and other dissolved organics. This can effect the reading because it absorbs light. So the checker needs to essentially read the color before it reacts with po4 powder so it can compensate.

Fwiw I shook the sample for 2 minutes and it didnt change the reading. Was on target.

 

[MnFish1]

Exactly as rtparty said. The sample of water has a color. Usually from tannis and other dissolved organics. This can effect the reading because it absorbs light. So the checker needs to essentially read the color before it reacts with po4 powder so it can compensate.

Fwiw I shook the sample for 2 minutes and it didnt change the reading. Was on target.

Tnats what I meant. The first vial is to get a baseline of the water - sorry it wasnt clear.

 

[rkpetersen]

Here are my own particular nuances when using the Hanna ULR phosphorus checker. I seem to get consistent and accurate results.

I use a small funnel to get all of the powder into the vial quickly.

I mix by tilting the vial back and forth rapidly for 90 seconds by the clock. I do not shake vigorously; this produces too many microbubbles. The powder does not dissolve as fast as some think; small particles may still be present at 1 minute. I check the vial against a backlight during the mix to see how well the dissolution is proceeding. When almost all of it is dissolved, I roll the vial to remove any remaining microbubbles and particles.
I don't mix for the full recommended two minutes. As noted, Hanna's timers are too tight and it's far too easy to get into shutoff which requires you to start over with another packet of expensive reagent.

Perhaps OP's initial high reading was artifactual due to scatter from incompletely dissolved reagent?

When I start the 3 minute countdown on the checker, I also start one on a regular digital timer, so I get an audio alert when the reading is available. The checker also shuts itself off too quickly after the test is done, easy to miss if you're multitasking.

If I don't trust a particular measurement for some reason, I start over, I don't retest the same cuvette that I already don't trust.

I use the same cuvette for the blank and test, keep the exterior scrupulously clean, and insert in the same orientation. Cuvette and cap get cleaned with rodi water shortly after each test.

 

[Skibum]

Here's my method for testing with the Hanna ULR checker:

1. Cut the package across the indicator line, make a funnel with the aluminum
2. Have the sample ready in the cuvette, wiped clean
3. Set a separate timer on my iPhone or kitchen timer for 2 minutes
4. Turn on the checker, drop the sample in immediately when it says "C1"
5. As soon as it says C2, take out the cuvette from the checker, pour in the reagent from the prepared package, close the cuvette and wipe.
6. Start the timer to countdown 2 minutes, all the while inverting the cuvette constantly, not shaking as this causes microbubbles.
7. As soon as the timer gets close to 0 I wipe the cuvette, drop it back in the checker and hit the button again.

It took a while to get this method, but it's accurate every time.

JM2C

 

[MnFish1]

Here's my method for testing with the Hanna ULR checker:

1. Cut the package across the indicator line, make a funnel with the aluminum
2. Have the sample ready in the cuvette, wiped clean
3. Set a separate timer on my iPhone or kitchen timer for 2 minutes
4. Turn on the checker, drop the sample in immediately when it says "C1"
5. As soon as it says C2, take out the cuvette from the checker, pour in the reagent from the prepared package, close the cuvette and wipe.
6. Start the timer to countdown 2 minutes, all the while inverting the cuvette constantly, not shaking as this causes microbubbles.
7. As soon as the timer gets close to 0 I wipe the cuvette, drop it back in the checker and hit the button again.

It took a while to get this method, but it's accurate every time.

JM2C

Hopefully you mean that in 7. That 'as soon as the timer gets close to 0 I wipe the cuvette, drop it into the checker and hit the button until the 3 minute timer starts working'. and then read the result after the 3 minute timer.

Because - if you just 'click the button' and dont hold it down for the 3 minute timer - it will give you an immediate reading - which is not a correct one.

 

[Fudsey]

if you just 'click the button' and dont hold it down for the 3 minute timer - it will give you an immediate reading - which is not a correct one.

This is what was happening to me. That was the reason for the initial post. Every time I tried to "Hold" the button, it would reset causing me to re-do the test. That's when I started using 2 vials.

 

[Skibum]

Hopefully you mean that in 7. That 'as soon as the timer gets close to 0 I wipe the cuvette, drop it into the checker and hit the button until the 3 minute timer starts working'. and then read the result after the 3 minute timer.

Because - if you just 'click the button' and dont hold it down for the 3 minute timer - it will give you an immediate reading - which is not a correct one.

Are you sure that's correct? I was under the assumption that the 3 minute timer is for the whole process. In other words, what really matters is that the reagent has had a 2 minute mix time. Not that it's sitting in the cuvette for 3 minutes after being mixed.

 

[rtparty]

Are you sure that's correct? I was under the assumption that the 3 minute timer is for the whole process. In other words, what really matters is that the reagent has had a 2 minute mix time. Not that it's sitting in the cuvette for 3 minutes after being mixed.

False. It must sit in there for 3 minutes AFTER you have mixed for 2 minutes already. The instructions state this. The reaction needs 5 minutes to give a correct reading per Hanna

 

[Skibum]

False. It must sit in there for 3 minutes AFTER you have mixed for 2 minutes already. The instructions state this. The reaction needs 5 minutes to give a correct reading per Hanna

DOH!

 

[rkpetersen]

DOH!

Is your phosphorus level usually quite low? This would make the absolute difference between what you read and the correct reading (obtained after an additional 3 minutes) relatively small. However at higher levels your numbers should be way off/low.

 

[rkpetersen]

This is what was happening to me. That was the reason for the initial post. Every time I tried to "Hold" the button, it would reset causing me to re-do the test. That's when I started using 2 vials.

When it's reading C2, you should just hold it down long enough for the 3:00 timer to appear on the display, and then let go. The timer will start counting down.

 

[XNavyDiver]

For those having trouble with short time out feature of the ULR. Do this first:

Make sure you pre cut the packet first. Tap the sides to gather the chemical into one corner. Cut and fold as shown above. I squeeze the sides in my fingers like an accordion to make sure all of the reagent is in a nice loose pile ready to pour. After zeroing the unit, just take it out, pour and shake for two minutes. Then place back in the unit the same orientation you had it during the zeroing phase. Press and hold the button down until 3 minute timer shows.
Using this technique, I have NEVER had the unit timeout on me. Easy peasy lemon squeezy.

 

[rkpetersen]

Okey dokey, smokey! :)

(I still recommend a funnel for maximum efficiency and minimum chance of error. These ones; they're perfect.)

https://www.amazon.com/20pcs-Mini-P...qid=1511742720&sr=8-8&keywords=perfume+funnel

 

[Krzydmnd]

Do you have a target phosphate number you are after? With the lowest and highest of your numbers you're at approximately. 015 and. 052 testing. I ran my checker multiple times and easy and ultimately just look for numbers between 5 and 20 on the LR checker and I don't worry as this is my acceptable target range.

 

[Fudsey]

When it's reading C2, you should just hold it down long enough for the 3:00 timer to appear on the display, and then let go. The timer will start counting down.

This is when I was doing it and it would shut off. It is working properly now.

 

[Skibum]

Is your phosphorus level usually quite low? This would make the absolute difference between what you read and the correct reading (obtained after an additional 3 minutes) relatively small. However at higher levels your numbers should be way off/low.

Interestingly enough my p04 went lower after doing the test the"right" way. Ugh. Months of invalid tests. Good thread

 

[MnFish1]

Are you sure that's correct? I was under the assumption that the 3 minute timer is for the whole process. In other words, what really matters is that the reagent has had a 2 minute mix time. Not that it's sitting in the cuvette for 3 minutes after being mixed.

that is not correct. The 2 minute mixing time comes before the 3 minutes 'vial sitting in the machine' - the test is read at 5 minutes...

 

[MnFish1]

Do you have a target phosphate number you are after? With the lowest and highest of your numbers you're at approximately. 015 and. 052 testing. I ran my checker multiple times and easy and ultimately just look for numbers between 5 and 20 on the LR checker and I don't worry as this is my acceptable target range.

Not sure which post you are directing this to. (I assume the Original Poster). If you do the test improperly, you cant be sure that the 5 and 20(or whatever result you get) on the checker are correct. The accuracy of the device itself is Accuracy @ 25°C/77°F ±5 ppb ±5% of reading (According to the Hanna). I admit - I do not understand the accuracy they quote - because depending on the reading 5ppb or 5% could be quite different - and they dont really explain their 'cut-off')

As RKPetersen said this is especially important if your P is elevated somewhat and you are trying to adjust GFO or dose PO4. Even using your example - if the reading was '20 ppb' - it could really be '25 ppb (or 15 ppb)'. If it was reading 20 ppb because you didn't do the test properly, and the 'true reading' was 5 ppb - you could cause problems. Of course - I dont test P very often using the checker - perhaps every 2-3 weeks. So if I get a result that is 'out of whack' it becomes more difficult.

 

[Fudsey]

My PO4 is very low now between 0-3 PPB which is effectively 0. In the OP I was asking because my meter wasn't allowing me to "Hold" the button to get timer. I found out it was a bad battery on a new unit. Ever since I replaced the battery, I have not had that issue. I am running a GFO/GAC combo in a reactor to keep it low as I have had issues in the past. Before starting the GFO, my readings were .1 - .18 PPM or higher.

When I did the OP I was reading the yellow quick sheet which says you can either use timer or wait the 3 min and the just push the button. With the auto off @ 2 minutes(as people have pointed out) I was doing the test too early to avoid this. That was the reason for 2 vials. so I could run the test again if it shut off. But I also noticed if I ran the test immediately after, it was lower. This is where I was getting confused. Now, knowing it should be run at the 5 minute mark, I am getting correct readings as I am sure were my 2nd or 3rd readings before because they were at about that mark.