Hannah phos checker timing

[downset21]

I’m curious if anybody else runs into the problem of waiting the two minutes for the mixing of the powder and the water sample leading to the Hannah checker shutting off. It makes me have to start all over. How long should I do that step of the prescribed two minutes are too long?

 

[NY_Caveman]

I always have the reagent cut and ready to pour before starting the process if that helps. I shake for 1:50 then tap the cap to get the bubbles to settle for 10 seconds. I also always have my phone timer running so I know where I am.

 

[Crabs McJones]

I’m curious if anybody else runs into the problem of waiting the two minutes for the mixing of the powder and the water sample leading to the Hannah checker shutting off. It makes me have to start all over. How long should I do that step of the prescribed two minutes are too long?

I found that it helps to have the powder packet already cut open before you start the test the checker should timeout after 3 minutes so if you have the powder packet ready push the button mix it as fast as you can and put it back in before the 3 minutes

 

[sghera64]

I’m curious if anybody else runs into the problem of waiting the two minutes for the mixing of the powder and the water sample leading to the Hannah checker shutting off. It makes me have to start all over. How long should I do that step of the prescribed two minutes are too long?

Can you clarify the problem you are having for us, please?

Is it:
1.) In C.2 mode, it is shutting off before the two minutes is completed, or

2.) you cannot complete the mixing/dissolution step in less than 2 minutes, or

3.) something else?

 

[jsker]

I use two cuvette, one with just the tank water and the other with the tank water and reagent. I test the tank water then the second cuvette. I also use a magnetic stirrer and stir the water with the reagent so that there is not staking involved, just spinning/stirring
If is mess up and press the button to long and the checker shuts off, no big deal

 

[downset21]

Can you clarify the problem you are having for us, please?

Is it:
1.) In C.2 mode, it is shutting off before the two minutes is completed, or

2.) you cannot complete the mixing/dissolution step in less than 2 minutes, or

3.) something else?

1. It shuts off before or right at 2 min

2. I am a master at mixing the solution

3. I’m simple minded

 

[jsker]

1. It shuts off before or right at 2 min

2. I am a master at mixing the solution

3. I’m simple minded

Use the second cuvette.

 

[Dawgvet]

Use the second cuvette.

I thought that was not recommended due to difference in cuvette shape/refraction

 

[Pmj]

I start the timer, then shake for 2 min (sometimes less if it's clear), then put it in at one minute left. Never noticed a difference in results.

 

[Reefltx]

I’m curious if anybody else runs into the problem of waiting the two minutes for the mixing of the powder and the water sample leading to the Hannah checker shutting off. It makes me have to start all over. How long should I do that step of the prescribed two minutes are too long?

You have 6 mins total.
Once C1 turns to C2 you have 3mins before the checker auto shut down. What I do is take the vial out at C2 and mix in the reagent. Mix for about 1:30-2:00mins then I start the timer count down on the checker.

 

[Randy Holmes-Farley Verified Community Expert]

I thought that was not recommended due to difference in cuvette shape/refraction

That’s correct. It can introduce errors if the curettes do not exactly match.

 

[Dawgvet]

I feel like a NASCAR pitcrew member when I’m running this test. As was stated above it helps if you have the packet open and ready to go before starting the test. Another thing that helps me is that I use a micro funnel to pour powder into cuvette. I don’t have to be as careful when pouring the powder.

 

[Dawgvet]

I should go hunting for my old scoopula (all of you that took high school/college chemistry should remember those things ), that way I can pre-pour the powder into it and make it faster to pour into cuvette.

 

[jsker]

I thought that was not recommended due to difference in cuvette shape/refraction

I have not ever had a problem.

 

[sghera64]

1. It shuts off before or right at 2 min

2. I am a master at mixing the solution

3. I’m simple minded

Thank you for clarifying. My recommendation is to return the unit and get a replacement. A few others have reported the same problem and it simply is not not the way the unit is intended to operate. It should remain on for at least 2-3 minutes. Mine shuts off after 2 minutes and 40 seconds.

We had a long thread a while back (even reached out to Hanna) about the criticality to the accuracy of the method that the actual time at which the reading is taken is 5 minutes after the reagent is introduced and mixing begins. So you need that full two minutes before starting the 3 minute timer. @MnFish1 can back me up on this.

Can you get the unity replaced?

 

[sghera64]

I have not ever had a problem.

+1

I checked mine by running repeat assays: first the way the method prescribes and then using two cuvettes (one to calibrate and one as a sample). I get the same reading +/- a few PPB. @jsker, have you also done this check?

 

[jsker]

+1

I checked mine by running repeat assays: first the way the method prescribes and then using two cuvettes (one to calibrate and one as a sample). I get the same reading +/- a few PPB. @jsker, have you also done this check?

Yes.

 

[Alfrareef]

I always have the reagent cut and ready to pour before starting the process if that helps. I shake for 1:50 then tap the cap to get the bubbles to settle for 10 seconds. I also always have my phone timer running so I know where I am.

Also...

 

[dede]

I use a timer on my computer and start the 3 min countdown as soon as the C2 comes on. Then add the reagent that I have ready to go and shake till I have about 15 seconds left at which point I add the vial and press the hanna black button. I then reset the timer so I do not forget to check the reading.

If I screw something up I do what others suggest and get a second vial of tank water to restart the test so I don't waste the reagent.

 

[sghera64]

I use a timer on my computer and start the 3 min countdown as soon as the C2 comes on. Then add the reagent that I have ready to go and shake till I have about 15 seconds left at which point I add the vial and press the hanna black button. I then reset the timer so I do not forget to check the reading.

If I screw something up I do what others suggest and get a second vial of tank water to restart the test so I don't waste the reagent.

If I understand what you wrote, then you are analyzing the sample about 3 minutes after mixing the reagent into it. Is that right?