riddle me this.... Hannah checker

[Eddie7144]

ok here we go again ! I had/ have a phosphate issue. running GFO in a reactor. i checked my phos. level 3 times in a row with the same sample. my reading were .20, .25, .30 I then got my salifet test kit , tested twice and with Salifer my reading was .03 both times. what is going on here ?

 

[250mixreef]

ok here we go again ! I had/ have a phosphate issue. running GFO in a reactor. i checked my phos. level 3 times in a row with the same sample. my reading were .20, .25, .30 I then got my salifet test kit , tested twice and with Salifer my reading was .03 both times. what is going on here ?

Have you cleaned the glass vials finger prints and such can give a false reading

 

[reefrf]

You can purchase calibration fluid for your Hanna checker if you want to validate the Hanna tester. I did & feel much more confident about the results.

 

[Eddie7144]

yes I clean the before and after use, didn't know about calibration fluid, where can I find some

 

[madweazl]

ok here we go again ! I had/ have a phosphate issue. running GFO in a reactor. i checked my phos. level 3 times in a row with the same sample. my reading were .20, .25, .30 I then got my salifet test kit , tested twice and with Salifer my reading was .03 both times. what is going on here ?

In the case of the Hanna checker and your results, it has +/- 5ppb resolution from what I remember so your results were in line with the margin of error on the kit (65-75ppb it looks like).

 

[XNavyDiver]

yes I clean the before and after use, didn't know about calibration fluid, where can I find some

http://www.bulkreefsupply.com/hi736-11-phosphorus-standards.html

 

[madweazl]

http://www.bulkreefsupply.com/hi736-11-phosphorus-standards.html

From the add:

"Acceptable results must be between 90 and 110 ppb at 25°C"

That doesnt seem to correspond to their claims of 5ppb accuracy

 

[XNavyDiver]

From the add:

"Acceptable results must be between 90 and 110 ppb at 25°C"

That doesnt seem to correspond to their claims of 5ppb accuracy

A Hanna rep is very active on the reef chem forum. Great guy and would gladly answer your question.

 

[madweazl]

A Hanna rep is very active on the reef chem forum. Great guy and would gladly answer your question.

Sorry about that, I didnt mean to make it seem like you were somehow culpable for the add.

 

[XNavyDiver]

Sorry about that, I didnt mean to make it seem like you were somehow culpable for the add.

No worries. I didn't take it that way.[emoji106]

 

[120reefkeeper]

@Hanna Instruments

 

[Hanna Instruments]

ok here we go again ! I had/ have a phosphate issue. running GFO in a reactor. i checked my phos. level 3 times in a row with the same sample. my reading were .20, .25, .30 I then got my salifet test kit , tested twice and with Salifer my reading was .03 both times. what is going on here ?

Hello, thank you for using our products! Are you using the HI713 Low Range Phosphate Checker or HI736 ULR Phosphorus Checker?

The HI713 has an accuracy statement of ±0.04 ppm ±4% of reading
The HI736 has an accuracy statement of ±5 ppb ±5% of reading

From the add:

"Acceptable results must be between 90 and 110 ppb at 25°C"

That doesnt seem to correspond to their claims of 5ppb accuracy

The standard for the HI736 is conservatively referencing 5% of the full scale, 200 ppb, which is +/- 10ppb.

For normal readings you use either ±5 ppb if your results are under 100 ppb or ±5% if your results are over 100 ppb.

Reasons for getting deviations outside of the accuracy statement can be improper cleaning of the cuvettes between tests, not getting the same amount of reagent into the cuvette for each test, not properly dissolving reagent powder (inadequate shaking), air bubbles inside the cuvette, add to much or too little water sample or not indexing the cuvette during C1/C2 phases. Make sure to follow our 8 Checker Best Practices

It can also help to use a 10ml syringe to add water sample to the cuvette, use a timer when mixing the reagent and purchase extra cuvettes to have a clean set to preform multiple tests in a row.

There is no way to quantify the measure of uncertainty when using a visual comparative chemical test kit. It is especially difficult to decipher low range phosphate concentrations by means of a color change. You need to be under a full spectrum light source and preferably against a white background to get the best results.

Phosphorus to phosphate conversion table

http://hannainst.com/resources/aqua...phate-conversion-table--hanna-instruments.pdf

Phosphates in your Reef Tank

http://hannainst.com/resources/aqua...ates-in-your-reef-tank--hanna-instruments.pdf

HI736 video

https://hannainst.wistia.com/medias/xhw3171vl9

 

[FloridaEsq]

I had the same problem, However, after reading the instructions again I realized I was not letting my test sample "rest" for three minutes. When I did it right the results were much more accurate. When the tester has you add C2 if you press and hold the button it will provide a countdown to the test.

 

[Hanna Instruments]

I had the same problem, However, after reading the instructions again I realized I was not letting my test sample "rest" for three minutes. When I did it right the results were much more accurate. When the tester has you add C2 if you press and hold the button it will provide a countdown to the test.

Yes this is very important as the test is time dependent and three minutes after two minutes of shaking the reagent is the optimal time for the chemical reaction to take place. If you wait any longer the reagent will not have proper time to react with your saltwater and give you off results.

 

[Mindi]

hint... put the reagent on a small clean folded piece of paper..when you remove the indexed cuvette to add the reagent, hold it in your polishing cloth....DRY the top rim of the cuvette with the cloth holding it....this stops the end of the paper from getting wet and interfering with the smooth addition of the powder....then just tilt the paper to run the powder into the cuvette. After you have mixed the powder well tap the cuvette on the bench to encourage any bubbles out.Then start the 3 minutes.

 

[Eddie7144]

thank you guys, I solves the problem. i wasn't hitting the bottom to get the there min timer ! lol I'm all good now. thanks

 

[Bruce Burnett]

thank you guys, I solves the problem. i wasn't hitting the bottom to get the there min timer ! lol I'm all good now. thanks

Great, this is one test that it does pay to follow the instructions exactly. I would never use a manual test kit for this.