Hanna Checkers
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Bpb
2500 Club Member
Wait...15-35? Is this two discrete readings? Or is that a range of readings you’ve found over a span of time? Because obviously it gives one number. Not a range. Either way I’d trust the ppb phosphorous meter. Smaller range of error if I’m not mistaken. Same reagent just programmed differently
Larry L
Valuable Member
If I'm doing the math right, then according to Hanna's advertised numbers:
The low range checker is +/- 0.04 ppm +/- 4% of the reading. So your zero reading could be as high as 0.04 ppm.
The ULR checker is +/- 0.005 ppm +/- 5% of the reading. So a reading of 35 could be as high as:
(35+5%) = 36.75 = 0.113 ppm
0.113 ppm + 0.005 ppm = 0.118 ppm
and as low as:
(35-5%) = 33.25 = 0.101 ppm
0.101 ppm - 0.005 ppm = 0.096 ppm
The low range checker is +/- 0.04 ppm +/- 4% of the reading. So your zero reading could be as high as 0.04 ppm.
The ULR checker is +/- 0.005 ppm +/- 5% of the reading. So a reading of 35 could be as high as:
(35+5%) = 36.75 = 0.113 ppm
0.113 ppm + 0.005 ppm = 0.118 ppm
and as low as:
(35-5%) = 33.25 = 0.101 ppm
0.101 ppm - 0.005 ppm = 0.096 ppm
OP
OP
The phosphorus will jump around. I tested it when I got home and it was 35 after being 17 last night. So I checked it again 5 minutes later and it read 20
jsker
Reefing is all about the adventure
It should not jump around that much, I have the ultra low phosphorus checker.
here is the Ultra low phosphorus conversion chart.
Randy Holmes-Farley
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Perhaps neither is accurate, but a value around 0.04 ppm fits all but one of the readings.
OP
OP
So I just tested it again and this time was 14
I got 94 on the calibration kit and as usual I cleaned the vials with their cleaning solution. So 3 different readings within 2 hours. 35,20, and now 14.
I got 94 on the calibration kit and as usual I cleaned the vials with their cleaning solution. So 3 different readings within 2 hours. 35,20, and now 14.
Randy Holmes-Farley
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Which is again consistent with an actual value around 0.04 ppm. [emoji3]
Bear in mind the “calibration” is not really that, but just a machine light absorption check. It really doesn’t say the device reads alk correctly.
Randy Holmes-Farley
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Are you following the phosphorus checker directions exactly as stated by Hanna? No shortcuts in timing, not using 2 cuvettes, etc?
To be clear, 5 minutes later is an entirely new sample, right?
U
User1
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Thou shall not cheat!!!
So which checker is accurate within reason? I have the 713 I believe and previous two readings are 0.25. Yesterday it read 0. 10. I can't imagine the phosphates actually going down since it is still a new tank that completed the cycle in March. April I turned on lighting and skimmer. April 15th moved the 40 breeder into it. I am going through the various diatom stage so was a bit surprised it was lower. I have read a couple sources around the net (you know how that goes) and several said don't use the 713 - need to use the one noted here. That is why I was asking and reading the phosphate threads.
That and the first time I used it I did your short cut with 2 cuvettes. One time deal and already been down that rat hole.
Edit: Checker actually displayed 0. 10 - nothing in the tenths...odd.
Randy Holmes-Farley
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Thou shall not cheat!!!
So which checker is accurate within reason? I have the 713 I believe and previous two readings are 0.25. Yesterday it read 0. 10. I can't imagine the phosphates actually going down since it is still a new tank that completed the cycle in March. April I turned on lighting and skimmer. April 15th moved the 40 breeder into it. I am going through the various diatom stage so was a bit surprised it was lower. I have read a couple sources around the net (you know how that goes) and several said don't use the 713 - need to use the one noted here. That is why I was asking and reading the phosphate threads.
That and the first time I used it I did your short cut with 2 cuvettes. One time deal and already been down that rat hole.
Edit: Checker actually displayed 0. 10 - nothing in the tenths...odd.
For values below about 0.04 ppm phosphate, the 713 is not useful and the 736 is likely better.
U
User1
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Thanks. Not sure if I need to go that low but I probably should have bought the right one the first time. Thanks!
OP
OP
Yes. 5 minutes once the the reagent hits the sample. I talked to Hanna yesterday and they believe I got a bad lot # of reagents. They’re sending me a new batch.
15-35 on the Phosphorous checker would be 0.046-0.107ppm phosphate. That level should be reflected on the Phosphate checker +- 4%. Were these tested off at the same time with the same batch of sample water?
Have you checked the dates on your reagents?
That all aside I would say the Phosphorous checker is generally accepted as the more accurate of the two especially at the low end of the range. They have also made a reference chart to reduce the need to do the math for conversion. https://hannainst.com/resources/aqu...phate-conversion-table--hanna-instruments.pdf
Tphill
Active Member
My hanna 736 has proven to be accurate. In April when I sent my first ICP test off, I also tested several things at the same time I collected the ICP sample. Hanna checker measured phosphorus at 7, which is .021 PO4. ICP test came back at 6.502 P and .01989612 PO4. Tested again yesterday, as I sent another test off. Hanna registered phosphorus at 9, or .028 PO4. Will see what the ICP is this time.
OP
OP
All the tests I’ve performed regarding this thread have been with 15 minutes of each other with different water samples from the same tank.
Tphill
Active Member
Ok, just got the ICP test back. Now I'm questioning the accuracy of the ICP, or Triton's additives. For phosphorous, ICP showed 737 and PO4 was 2.237. As stated earlier, my Hanna checker had phosphorous at 9, PO4 at .028. Don't think the checker is off that much, and really don't think my PO4 is 2.237.
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Do you have a link to the report?
