Marine Hanna phosphorus tester to measure RO/DI water

Fishy888 · Dec 19, 2022

Can I use my Hanna checker to test RO/DI water? It’s the marine checker. I know they make a freshwater version but I’d rather not buy it if I don’t need it.

Waters · Dec 19, 2022

I use it to test my freshwater tanks all the time so I don't see why not.

Randy Holmes-Farley · Dec 19, 2022

Waters said:
I use it to test my freshwater tanks all the time so I don't see why not.

Does that mean it is accurate there?

I've not tested it myself, but here's what Hanna says:

"
While the HI713 LR Phosphate Checker will work for any saltwater aquarium, the unit has an accuracy statement of ±0.04 ppm ±4% of reading. This means if your HI713 LR Phosphate Checker displays a result of 0.08ppm, the measurement uncertainty is from 0.04ppm to 0.12ppm, which can be problematic for certain reef aquarists. If your reading is 0.00ppm than you phosphates can be as high as 0.04 ppm. Displaying the results in part per billion phosphorus gives a narrower range for detection, but increased accuracy at low range phosphate concentrations desired by many reef tank hobbyists.

The HI736 is labeled “marine” because it is specifically designed for saltwater and utilizes an absorbance curve for marine environments, while the HI713 can be used in either freshwater or saltwater. The HI736 ULR Phosphorus Checker has a range of 0 to 200 ppb PO₄-P orthophosphate as phosphorus, which correlates to 0.003ppm to 0.613ppm PO₄3ˉ. The HI713 LR Phosphate Checker has a range of 0.00 to 2.50 ppm PO₄3ˉ orthophosphate."

I think my Hanna Po4 checker took a dive.

Thanks Hot rocks, But I now know what I was wanting. glb, this is what I have going also. Haven't graduated to a full sps tank yet ! But i'm learning .This tester has worked just fine for my needs at this time. So now I have confidence the tester was working. Sure enough I way overdosed. I...

www.reef2reef.com

taricha · Dec 19, 2022

I found that when I diluted saltwater with distilled and measured it with the hanna checker that it went fine down to like 25% saltwater, 75% distilled.
But then the measurements got weird giving unexpected results when I did just distilled.

taricha · Dec 19, 2022

Here's the data I was referring to...
Spiking just distilled water gave me nonsense, but diluting saltwater down to 20% still worked pretty well...

taricha said:
Here's a quick look at some data for those who want to see what the hanna P test does vs calculated stock additions, and how it compares to hanna uncertainty statements.
Hanna's accuracy statement for the ULR P checker is "+-5ppb +-5% of reading" without any clarity as to whether you should take the larger of the two uncertainties or add them.

First, here's one I did with new Instant Ocean spiked with Seachem Flourish Phosphorus. This was measured a day after the spike.
View attachment 2422478
The error bars shown are +-5ppb, and the black line is the Ideal case if I make perfect solutions, the stock product is completely accurate, and there no loss in the sample.

Here's me spiking my tank water with known additions of monopotassium phosphate (KH2PO4) - blue data.
The yellow data points are what happened when I tried to run it in straight distilled water (spiked with P) - it seems to fail completely.
View attachment 2422485
(error bars here are +-5%)

And after seeing the failure with straight distilled water, I wanted to know for sure if I could get away with diluting saltwater with distilled (which has seemed to work for me before). Tagging @Dan_P and @Rick Mathew on this one.

Tank water, spiked with P, diluted from 100% to 80%, 60% etc with distilled water. Seems to work fine, and you can likely get away with diluting an out of range tank water sample by 1/2 or 1/4 with distilled water, and the hanna test will still give pretty much expected results. Just don't run it in straight distilled water.
View attachment 2422493
(error bars +-5ppb)

If you take the common interpretation of of hanna's accuracy statement: "+-5ppb" or "+-5%" whichever is larger, then the accuracy statement covers almost all the data above, as seen by the error bars. If you take the more conservative interpretation to add +-5ppb and +-5%, then all points shown above fall inside, even with whatever unknown errors are hiding in my sample mixing, or stock purity, or loss in the sample.

Overall, the hanna ULR P kit is the most impressive chemical test in the hobby, IMO.

Waters · Dec 19, 2022

Randy Holmes-Farley said:
Does that mean it is accurate there?

I've not tested it myself, but here's what Hanna says:

"
While the HI713 LR Phosphate Checker will work for any saltwater aquarium, the unit has an accuracy statement of ±0.04 ppm ±4% of reading. This means if your HI713 LR Phosphate Checker displays a result of 0.08ppm, the measurement uncertainty is from 0.04ppm to 0.12ppm, which can be problematic for certain reef aquarists. If your reading is 0.00ppm than you phosphates can be as high as 0.04 ppm. Displaying the results in part per billion phosphorus gives a narrower range for detection, but increased accuracy at low range phosphate concentrations desired by many reef tank hobbyists.

The HI736 is labeled “marine” because it is specifically designed for saltwater and utilizes an absorbance curve for marine environments, while the HI713 can be used in either freshwater or saltwater. The HI736 ULR Phosphorus Checker has a range of 0 to 200 ppb PO₄-P orthophosphate as phosphorus, which correlates to 0.003ppm to 0.613ppm PO₄3ˉ. The HI713 LR Phosphate Checker has a range of 0.00 to 2.50 ppm PO₄3ˉ orthophosphate."

I think my Hanna Po4 checker took a dive.

Thanks Hot rocks, But I now know what I was wanting. glb, this is what I have going also. Haven't graduated to a full sps tank yet ! But i'm learning .This tester has worked just fine for my needs at this time. So now I have confidence the tester was working. Sure enough I way overdosed. I...

www.reef2reef.com