Different results between HI713 vs HI736

[11shuki]

i made two tests with the same water
HI713 i have got 0.00 ppm i rechecked the result with millwaki and i got the same result.
HI736 i have got 25x3.066/1000=0.076
why there's a different?

[alessandro]

i made two tests with the same water
HI713 i have got 0.00 ppm i rechecked the result with millwaki and i got the same result.
HI736 i have got 25x3.066/1000=0.076
why there's a different?

Same here.

[bbalak]

It is my understanding the HI736 is a much more precise tester. It tests in the PPB range, while the HI713 is testing in the PPM range. There's a big difference between a million and a billion.

[reuvenp9]

i made two tests with the same water
HI713 i have got 0.00 ppm i rechecked the result with millwaki and i got the same result.
HI736 i have got 25x3.066/1000=0.076
why there's a different?

I have the same problem.

[reuvenp9]

bump

[xp964]

Still checking on this... Jess (reef sales) has been out sick but I should hopefully have an answer tomorrow.

Thanks,

[alessandro]

the problems reside in reagents.
If you, with your checker, try to use merck,elos,tunze,rowa,DD, (all are the same) reagents ( 10 drops of reagent 1 and 1 spoon reagent 2) than you will get super reliable and consistent values.
All we need is new, good, reagents.
With the new liquid reagent alkalinity checker is very reliable.

[xp964]

I apologize for the delay but I checked with the Chemistry Department on this question. Here is what they had to say:

"The difference between the readings are pretty much within the specifications of both meters
HI 713 Accuracy ±0.04 ppm ± 4%
HI 736 Accuracy ±5 ppb ± 5%

Once the accuracy of the meters is taken into account that the readings are almost identical. In regards to the 0.01 difference between them that could be caused by variation between cuvettes or temperature.

Our meters are not designed to work with anyone else's reagents. I would not trust the readings using other manufactures reagents. I would discourage people from doing this."

Any further questions, please contact our tech support department: 1-800-426-6287.

Regards,

[alessandro]

"The difference between the readings are pretty much within the specifications of both meters
HI 713 Accuracy ±0.04 ppm ± 4%
HI 736 Accuracy ±5 ppb ± 5%



Ok, so the "Chemistry Department" states that a difference from a reading of 0.00 and a reading of 0.07 is acceptable....:lolspin::thumbsup:

[shifty51008]

Ok, so the "Chemistry Department" states that a difference from a reading of 0.00 and a reading of 0.07 is acceptable....:lolspin::thumbsup:

according to those reading yes they are the same. issue in the +-.04 and +-5% and they come out the same.

[pszemol]

Ok, so the "Chemistry Department" states that a difference from a reading of 0.00 and a reading of 0.07 is acceptable....:lolspin::thumbsup:

Looks like the sample with 0.07ppm content of PO4 is simply below the usable sensitivity of the HI-713 meter. That's all.

And it makes sense, considering its full scale is quite large in reef context: 2.50 ppm.
The reading of 0.00 ppm for a true sample containing 0.07ppm is only 2.8% error of full range (stated error is +/-4%).

Think about it - it is like you would take a pressure gauge with the full scale of 250 psi and expected it to be accurate measuring the given pressure of 7psi. I bet you it would show zero as well.

For reefers with low PO4 readings the HI-713 seems to be not that useful.

[LesMartin]

Can anyone get CONSISTENT readings using the phosphorous checker ? I first thought mine was a bit iffy when I was using it to test the output from a phos reactor. The phos reactor output was showing 8ppb but when I tested the tank i got a reading of 17ppb. I did a couple of back to back tests of the tank water again and got wildly different readings ( 3ppb and 20ppb). I then did 5 consecutive readings from the tank and each and every one was different varying from 0ppb to 23ppb. I then sent this back to Hanna UK and they tell me it tests ok using their standard solutions. So, 6 more consecutive tank readings later and i got 0ppb, 17ppb, 11ppb, 27ppb, 8ppb. This thing is practically useless.

[pelagic7]

yea... I agree, I got 0ppb, 30ppb, 12ppb on the same day before... here's what I do to make sure the reading is ok.

1. Do the test like normal, but have another Cuvette w/ same sample ready
2. After the normal test, record the value, and do it again, but this time use the Cuvettes from step 1 as C1, and use the Cuvettes you did the test w/ as C2. Note: you don't need to wait 3 mins for this, simple press but not hold the button.
3. Compare the results, they should be close or the same, if not, it means there was something wrong when you did the test, maybe the micro bubble or Cuvettes wasn't clean enough.

I hope they have the liquid regent for the P checker like the ALK one.. that will be awesome.

[Bayliner]

I hope they have the liquid regent for the P checker like the ALK one.. that will be awesome.

Are they working on this ? I agree that would be much better

[MHG]

is measuring down to PPB really necessary? is the &#^ the "meter to get" or is the 713 fine...?

[outssider]

they cost $ the same amount....why not get the one that is more accurate/precise.....

[xp964]

Are they working on this ? I agree that would be much better

Hello Bayliner,

Liquid phosphate reagent is not stable enough to produce commercially, it lasts less than a week before it degrades.

Hanna

[oki_reefer]

I was having similar issues and called Hanna. The HI736 is more accurate. There is a conversion factor that is to be applied to the HI736 results to give the HI713 results. Take the HI736 results and multiply by 0.003.

[James77]

is measuring down to PPB really necessary? is the &#^ the "meter to get" or is the 713 fine...?

You convert it to ppm by dividing by 1000, so it ends up being far more accurate.

[James77]

Ok, so the "Chemistry Department" states that a difference from a reading of 0.00 and a reading of 0.07 is acceptable....:lolspin::thumbsup:

If it is within their stated accuracies that they dislose, why would it not be acceptable ;). Or were you expecting a perfect tester at $40?

Simple, get the ultra low range one, it measure in ppb and is far more useful to us.