Hanna Phosphate ULR tester accuracy?

[LeonardTheWrasse]

Hey,

I've been struggling with phosphate issues for a while, and have been using GFO.

I set the reactor up in the new tank last night, and before this I tested the phosphate, it was reading 0.90, so I assume it was higher than that.
This morning I tested twice, and it was reading 0.22 both times.
I then took a sample to my LFS, and they tested the water 5 times, and the readings were as follow, 0.78, 0.24, 0.90, 0.20, 0.90. All from the same batch of water, and the tests were all performed exactly the same, I was watching them do the tests the entire time.
On the very high readings the water did not turn the shade of blue that you see on these tests when the phosphate is testing so high.
Both the testers themselves are under a year old, and the reagents were all in date.
My (2) corals are doing very well, so that makes me think that the phosphate is not too high, but I'm not sure.

What should I do to get an accurate reading, and is this a common issue with the Hanna testers?

 

[Borat]

Hey,

I've been struggling with phosphate issues for a while, and have been using GFO.

I set the reactor up in the new tank last night, and before this I tested the phosphate, it was reading 0.90, so I assume it was higher than that.
This morning I tested twice, and it was reading 0.22 both times.
I then took a sample to my LFS, and they tested the water 5 times, and the readings were as follow, 0.78, 0.24, 0.90, 0.20, 0.90. All from the same batch of water, and the tests were all performed exactly the same, I was watching them do the tests the entire time.
On the very high readings the water did not turn the shade of blue that you see on these tests when the phosphate is testing so high.
Both the testers themselves are under a year old, and the reagents were all in date.
My (2) corals are doing very well, so that makes me think that the phosphate is not too high, but I'm not sure.

What should I do to get an accurate reading, and is this a common issue with the Hanna testers?

Can you describe how you run Hanna ULR test (in details):
- add tank water to the vial
- open sachet and make it ready for use
- wipe the vial with fibre cloth, put vial into colourimeter
- take vial out of colourimeter, add reagent and swirl the sample water for 2minutes
- wipe the vial with fibre cloth, put the vial back into colourimeter
- long press the button
- wait for 3 minutes for results to be displayed

Use citric acid to clean the via after test.

 

[LeonardTheWrasse]

- Clean vial with citric acid and vinegar before adding tank water.
- Wipe vial out with micro-fibre cloth.
- Add tank water to the vial.
- Wipe vial with microfibre cloth, put vial into colourimeter.
- Take vial out of colourimeter, add reagent and shake sample for 2 minutes.
- Wipe vial with microfibre cloth, put vial back into colourimeter
- Press button for 3 seconds.
- Wait for results to be displayed.
- Repeat cleaning process and put vial and colourimeter back in storage.

I thought I was being too careful with how strict I am about it and much I was cleaning the vial and everything, but I think it's probably better to be overly cautious.

 

[george9]

I may be misunderstanding but your two tests at home both gave you .22PPM and the LFS tested 5 separate readings with each of the tests they did? It sounds like a problem with the store's tester more than yours to me. If you got a repeatable .22PPM with each test you did at home, I'd ignore the LFS results completely lol especially when their tester can't even give a result in the same ballpark twice.

The fact that you didn't see that blue tint in the vial is a red flag to me...especially with concentrations as high as you were testing. I see that blue tint start to show up if the water sample is about .20PPM and upwards. Was this with the store's tests?

 

[LeonardTheWrasse]

I may be misunderstanding but your two tests at home both gave you .22PPM and the LFS tested 5 separate readings with each of the tests they did? It sounds like a problem with the store's tester more than yours to me. If you got a repeatable .22PPM with each test you did at home, I'd ignore the LFS results completely lol especially when their tester can't even give a result in the same ballpark twice.

The fact that you didn't see that blue tint in the vial is a red flag to me...especially with concentrations as high as you were testing. I see that blue tint start to show up if the water sample is about .20PPM and upwards. Was this with the store's tests?

Yes, my multiple tests at home gave me a .22 reading.
I took a sample to my LFS just to double check what the reading was, and they tested 5 times with varying results.

The store's tests were testing very high without the blue tint in the water. With my tests there was almost no blue tint, and if there was I couldn't pick see it.

 

[Dan_P]

Yes, my multiple tests at home gave me a .22 reading.
I took a sample to my LFS just to double check what the reading was, and they tested 5 times with varying results.

The store's tests were testing very high without the blue tint in the water. With my tests there was almost no blue tint, and if there was I couldn't pick see it.

Stop going to that store for water tests. They seem to be having a problem testing and don’t know it. The Hanna Checker is likely OK.

 

[DanyL]

The lack of blue color tells me the stores vials are likely scratched, obscuring the sensor and thus giving varying results when aligned differently in the checker.

 

[LeonardTheWrasse]

I've tested three times again now, following the same procedure I outlined in post #3, and my phosphate is reading at 0.13 PPM, 0.17 PPM and 0.13 PPM respectively now.

If anything, this is just a testament to how well GFO works when used correctly. It has taken my phosphate from reliably at and presumably over 0.90 PPM to so much lower in just 2-3 days.

 

[Borat]

I've tested three times again now, following the same procedure I outlined in post #3, and my phosphate is reading at 0.13 PPM, 0.17 PPM and 0.13 PPM respectively now.

If anything, this is just a testament to how well GFO works when used correctly. It has taken my phosphate from reliably at and presumably over 0.90 PPM to so much lower in just 2-3 days.

Yeah, GFO drops phosphates very quickly - when I used it to control phosphates I rather wanted the reverse: slow decrease of phosphates. This is probably only achieved by reducing the flow through the reactor..

I don't use GFO nowadays - and actually I dose phosphates to keep them at 0.1ppm.

 

[e34stx]

i thought reducing po4 too quicky is quite bad for the corals, resulting in rtn and stn?

 

[Randy Holmes-Farley]

i thought reducing po4 too quicky is quite bad for the corals, resulting in rtn and stn?

It might be, but no method needs to drop phosphate rapidly. Some can if you use a relatively large amount, but using less can make it go as slow as you want.

 

[doubleshot00]

May be the reagents. I've had a few bad batches. If the reagent powder looks wet or damp then its no good.

Also i wouldn't clean out with citric acid each time. Just rinse with ro water and let dry upside down.

 

[tapeworm123]

Is citric acid phosphate free? My guess is no. Are you using the correct phosphate checker and reagent as the store ?

 

[Billyreef-ita]

Do you see algae in the tank? Because if the tank is ok, I wouldn’t do anything.
Sometimes the medicine is worst than the disease….I lost many corals with GFO absorbing PO4 too quickly

 

[Borat]

Is citric acid phosphate free? My guess is no. Are you using the correct phosphate checker and reagent as the store ?

Purpose of citric acid wash is to dissolve blue chemical that stains the vial - so that it can then be rinsed off with RO DI water.. not sure how you see link between citric acid and phosphates.

 

[ReeferFive-0]

Purpose of citric acid wash is to dissolve blue chemical that stains the vial - so that it can then be rinsed off with RO DI water.. not sure how you see link between citric acid and phosphates.

I've had good luck so far by just rinsing out the glass vial with RODI water directly after testing and storing the vial filled up with RODI water between tests. I haven't had the Hanna checkers very long, but have not had to resort to citric acid yet.

 

[tapeworm123]

Purpose of citric acid wash is to dissolve blue chemical that stains the vial - so that it can then be rinsed off with RO DI water.. not sure how you see link between citric acid and phosphates.

Your testing for ppm or ppb. Mine is ppb if the citric acid has phosphate in it. You can rinse it a million times never going to get vial clean again.

 

[Borat]

Your testing for ppm or ppb. Mine is ppb if the citric acid has phosphate in it. You can rinse it a million times never going to get vial clean again.

:-|... I better talk to my pet chicken...

 

[shadyraro]

After I do my hanna tests I rinse the vials in tap water, then shake out the excess and let them dry out.
Before I test I fill and empty the vials 3 times in tank water to rinse them, then do the test.