New Phosphate ULR vs Phosphorus ULR

Inkbird
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Ecoscape Reef Rock
For what it’s worth, I asked Hanna and they said the units are the same just reporting different numbers. Then I called back and found out the standards and reagents aren’t interchangeable like alk with the dKH unit and the ppm unit. That makes me think there is a mathematical difference and obviously different reagents for the new PO4 Ultra Low Range ppm and the older Phosphorus Ultra Low Range ppb.
 
I think BRS did a video of the phosphorous ULR. I seem to recall that the the phosphorous ULR, although requiring conversion calculations was a bit tighter on the range read. I'm in the market as well since the Salifert reads non-detectable and I think having some measurable phosphate is important to tank health (.05 ppm range).
 
do you have a link to both on the hanna site? i can only seem to find one.


J.
 
I like not needing to convert, but hopefully it's not more accurate and consistent because I'd have to get it!
 
Top Shelf Aquatics
So what I can see from instrument info.

HI774 Phosphate ULR 0 to 900 ppb range - 10 ppb resolution, +/- 20 ppb accuracy
HI736 Phosphorus ULR 0 to 200 ppb range - 1 ppb resolution, +/- 5 ppb accuracy

I guess it matters only if there's an inherent inaccuracies in calculating phosphate from phosphorus. I bet there's something on here.

https://www.reef2reef.com/threads/p...hi713-and-hi736-free-conversion-table.317886/

This is better. So yes it does look like the Phosphorus ULR provides a more sensitive reading. Not sure if it's that important and even Hanna says only for ULN systems. Let's see...if the 736 phosphorus range is 200 ppb max that's a max phosphate reading of 0.6 ppm with max error of 0.02 ppm after converting vs 0.9 ppm and max error of 0.1 ppm and for the 774. If I had the 774 and not into ULN I'd be fine with it, since I'm buying new, I'll probably go with the 736 and get my calculator out.

Adding a note: at the low end of the range - 0 on the 774 could be .02 ppm while 0 on the 736 could read almost .01 ppm. So even with that, I'm thinking unless I'm really into ULN type values of phosphate <.03 ppm, I'm personally fine with either model (assuming my math is correct).
 
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Orphek OR3 reef aquarium LED bar
What good is some extra accuracy when a quarter of tests are rushed and failed due to 2 min time limitation on the Phosphorus one?
 
BRS
I have both the 713 and the 736, and find myself using the 713 most of the time. If I get a reading that seems off, I then go to the 736. After factoring out user error, they usually correlate pretty closely.

NOTE, I was referring to the 774 above, not the 713. I have both 774 and 736, and use the 774 most of the time.
 
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foxt said:
I have both the 713 and the 736, and find myself using the 713 most of the time. If I get a reading that seems off, I then go to the 736. After factoring out user error, they usually correlate pretty closely.
Click to expand...
Can I ask why you prefer the 713 for the initial test?
 
tyuksel said:
What good is some extra accuracy when a quarter of tests are rushed and failed due to 2 min time limitation on the Phosphorus one?
Click to expand...
What 2 minute time limit? I just ordered this one and haven’t used it yet.
 
Tidal Gardens
If you already own the older HI736 Phosphorus ULR checker is there any reason to buy the new one other than converting it? Which isn't even a problem as I have the conversion chart right on my testing bench. I guess they brought this new one out if you are purchasing a phosphate checker for the first time?
 
Quietman said:
Can I ask why you prefer the 713 for the initial test?
Click to expand...
Whoa! Glad you asked,because I am wrong! I have the 774, not the 713. So I test with the 774, then use the 736 when there is an issue.
 
tyuksel said:
What good is some extra accuracy when a quarter of tests are rushed and failed due to 2 min time limitation on the Phosphorus one?
Click to expand...

I would be most concerned in measuring values around 0.03 ppm. Assuming the manufacturers specs are correct, the accuracy difference there is Big as a fraction if the value itself.
 
AS
foxt said:
Whoa! Glad you asked,because I am wrong! I have the 774, not the 713. So I test with the 774, then use the 736 when there is an issue.
Click to expand...
LOL...ok same question. Curious why you use the 774 first instead of the "more accurate" 736. Is the procedure easier? Quicker test? I haven't bought mine yet, and generally I'd go more accurate but like to know if there's something else to consider with real world experience.
 
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Well, I asked this question because the one I currently own the 736 is no longer reporting repeatable values from tank water or the HI standards. I did some math yesterday and from posts above, the 736 still seems to be a little more accurate than the 744. For what it’s worth, my 736 shuts off after 3 minutes not 2. Don’t know why, because the Hanna website still indicates 2 minutes. I bought it a long time ago, but after everyone was complaining to Hanna that the test requires you to shake the vial for 2 minutes and the meter shuts off in 2 minutes. Anyway, it doesn’t read accurately anymore. Not sure if I’ll buy the 744 or get the 736 again.
 

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