Hanna phosfaat checker problem

[varke]

I bougt a hi 731 checker from Hanna and when i use it the reagens seems to make black/bleu particals so i can not measure it.
The reagens of two batches do the same and expire date is 06-2016
I see no particals in the curvet before adding the reagens.
my old test is from salifert and there is no color ore particals in that test.
i think it could come from plancton as i am running ats only for 2 years.
any of you know of this problem?

Greetings
Eric Jan

[Pny]

Just let the unreacted reagent settle to the bottom where it will not affect the measurement.

[Bacon]

I've used the Hanna Checker quite a bit and never seen any colored particles precipitate. There is sort or a detailed process you have to follow to make this test work right, consistently:

Fill the vial with the water sample
Prepare the packet (before zeroing out the meter)
- loosen up all the reagent by tapping/squeezing it with your finger while rotating the packet (move the air around)
- hold the packet with one corner down and keep tapping to get all the reagent in one corner
- Cut the packet with a scissors on the 2 top edges (opposite the corner where the reagent is settled)
- open the packet by grabbing the 2 side corners and wiggling it back and forth gently until it opens like a mouth
- this creates a spillway for pouring out the packet, using the top edge where the 2 cut edges meet

Wipe the cuvette with a clean glasses-cleaning cloth
turn on the meter, wait until it reads C1
insert cuvette
Press the button and release
when it zeroes out, it will read C2, the you have exactly 3 minutes to do the following (I use a timer)

- take out cuvette and open
- carefully pour in reagent
- cap cuvette
- with practice, this above process should take about 20-30 seconds.
- hold cuvette horizontal and rock it back and forth. Do NOT shake vigorously. Just keep it rocking to make the air bubble more the reagent back and forth and get it all dissolved. This usually takes right at about 2 minutes - it should all be dissolved. (use a timer)
- wipe cuvette again with glasses cleaning cloth
- insert cuvette into meter
- press AND HOLD button for 3 seconds until the meter reads 3:00 and then starts counting down.

Now the hard part is over. Set your timer again for 3 minutes so you don't forget to read the meter, as it will time-out after a few minutes.

[varke]

I tryed to shake it hard and it all disolved but the outcom was 0.4
Then i put in the salifert test in the checker and it was 0.17
than i put in osmose in one curvet and my tank water no reagent in it and it was 0.09.
So now some active carbon in the tank and test in a few days

[Bacon]

Do NOT shake vigorously. Just keep it rocking to make the air bubble more the reagent back and forth and get it all dissolved. This usually takes right at about 2 minutes - it should all be dissolved. (use a timer)

Do NOT shake it, at all. This is your issue - you end up with tiny bubbles that don't find their way to the top in 3 minutes, and will also stick to the cuvette, both of which throw off the reading.

All you need to do after you pour in the reagent and cap it is you invert the cuvette about 2 times per second, gently.

[varke]

5780

This happend when i do easy shaking
Picture is jellow from tl light.
You see the particals in right curvet.
When measuring this i got 0.84
After waiting some time i measured again and it was 0.41
Hope the active carbon makes water clearer so i can measure again and get an normal reading.
I also take a cup of water and let it stand for some time so detritus can sink before measuring.

[Bacon]

As far as I know, you cannot take multiple measurements over time with the Hanna meter. You only have one shot. You zero the meter with the tank water sample, add the reagent and mix for 2 minutes, then set it in the meter for the 3 minute period, and then the meter takes the reading.

Using one cuvette for the tank water sample (zero cuvette) and another for the testing sample can result in errors - this is the only way you could test the same sample multiple times, but you can't do this - that's not why they give you 2 cuvettes (even though it seems like that is what you are supposed to do - you are not)

[varke]

Oke Thanxs.
I used to curvets.
I wil try it in one.

[Bacon]

No problem

They give you 2 cuvettes in case one get stained and you need to clean it. On that note, you need to clean and rinse the cuvette immediately after the test is done, or else the reagent will stain the vial and throw off future tests.

What I do is run really hot water through it, I fill and dump about 15 times and give it a vigorous shake each time, then rinse with some RO water. Hanna sells a chemical that you are "supposed" to use to clean the cuvettes, but I have never found a need for it as long as you clean the cuvette right away.

I bought extra cuvettes also and then tested 2 samples back-to-back, one in a new cuvette and one in a year-old, heavily used one, and they tested the same.

Now, if you have the ultra-low phosphorus meter, things change. With that tester, you actually have to mark the cuvette so that you know it's rotation point in the meter, and make sure that when you zero the cuvette and then read the sample that it is in the same rotational position, because the variations in the thickness of the glass cuvette will actually cause the readings to differ significantly.