Hanna checker help

[Darth.Daddy12]

You don't use RODI water. C1 is sample water, unreacted tank water. C2 is the same cuvette with the same sample, with the reagent added.

I don’t have it so guess it’s different testing then some others.. so then I would only rise with rodi after testing and wipe dry with the towel.

I still say he’s using the wrong device at this levels.. but no reference as to time between the test either so it could actually no be bad readings but changes in the tank actually happening at those times..

 

[Darth.Daddy12]

This is the Hannah you have ? .3 is within scope. I get very consistent results mine although my system is a ULN . I rinse my curvette with rodi very well and shake out any remaining water vigorously.

I don’t have the UlM I have a couple of the others for now and they are two part rodi and tank mixes.. I was assuming the ULM was same testing protocol.. that was my mistake..

 

[Sierra_Bravo]

I just pulled mine out and no where does it say to do this.. you are using rodi water for the test itself anyways so this can’t alter the result.. in fact my instructions on 2 Hanna’s neither ones says anything about rinsing at all..

Unless you're testing your RODI water for phosphates, you would not be using RODI water in any part of this test except rinsing after it is done. A pre-rinse with the tank water you are testing is perfectly logical and will not impact the accuracy of the test.

 

[W1ngz]

@Rpc07 I'm trying to find the video and failing miserably, but one of the Hanna videos I've seen makes mention of indexing, or aligning the cuvette the same way for both C1 and C2. They mention always putting the cuvette with the 10ml lettering facing the front to eliminate any refraction errors from the glass that are possible if it's oriented differently between the tests.

Edit: Found it. This is for the 736, but I can't see any reason it wouldn't apply to all of their meters, especially in this case as the 774 is basically the 736 but does the math for you.

It's at the 10 minute mark of this vid:

 

[Rpc07]

I have read through all the comments to this point and I will also note I left some info out of my original post and have also seen some good debate.

I always index the cuvette (10ml in front)
I rinse with test water before the test
I fill the cuvette so the bottom of the meniscus is at the top of the 10ml line
I DO NOT check for air bubbles before the 3 minute count down and I’m am going to implement that into my routine.

For the people arguing if I am using the correct device I certainly am, I am using the Hanna HI774 which has a range from 0.00 to 0.90. How is 0.3 not in that range?

The inaccurate results we from tests performed daily so usually 23-24 hours between tests.I always test the tank before i feed frozen so that doesn’t alter the result. I find it very odd my tank would be .34 one day and the next .03 and then the third day .28

 

[saltyhog]

The difference between 0.34 and 0.29 isn't surprising at all in two tests 24 hours apart. Neither is the 0.26 In fact the first two are potentially within the accuracy range of the device....IE. 0.34 could actually be 0.31 and 0.29 could actually be 0.32 if you allow for the checker's stated range of accuracy.

The 0.19 and 0.03 are the ones that are the head scratchers!

 

[Rpc07]

The difference between 0.34 and 0.29 isn't surprising at all in two tests 24 hours apart. Neither is the 0.26 In fact the first two are potentially within the accuracy range of the device....IE. 0.34 could actually be 0.31 and 0.29 could actually be 0.32 if you allow for the checker's stated range of accuracy.

The 0.19 and 0.03 are the ones that are the head scratchers!

I completely agree, I’m fine with the higher readings day to day.

 

[W1ngz]

It's clearly not procedural. If you put the results in sequential rather than numerical order, (and maybe discard the .03) does it show any pattern? Increasing or decreasing?

 

[Rpc07]

It's clearly not procedural. If you put the results in sequential rather than numerical order, (and maybe discard the .03) does it show any pattern? Increasing or decreasing?

Yes without the few oddballs it is decreasing. .34 to .28 to .26 and then the .03 and .19 then back to .28

 

[W1ngz]

My vote in that case then would be some sort of contaminant or an 'oops' since the two anomalies are back to back. I'd keep doing the daily testing and see if it happens again.