HI-736 zero readings with LOT:H066

[vsutarov]

I compared with 2 more Hanna phosphate checkers HI96713 and HI93713.The were giving 0.04ppm PO4 readouts and HI736 was always giving me zero.For 0.05ppm PO4, HI736 was showing 0.01ppm(3ppb=0.01ppm).So my Hanna HI736 was starting to show phospahtes above 0.05ppm what is not acceptable to me.I was writing to hanna support but no luck,they were sayng that was normal.I am using Hanna 736 checker for long time and this is the second time I had bad LOT,the other bad LOT was H:025 but Hanna sent me another LOT imedeatly than.I know that the reagenses from this batch are not good,I can also tell from my tank.If Hanna can not help me,I am asking if someone has this LOT:H066 please confirm if the readouts are low.
Thank you

 

[dealseer]

Yes, I have this same issue.

 

[vsutarov]

Do you have this issue with the same LOT?

 

[dealseer]

Yes

 

[vsutarov]

If you haven’t already,please report your issue to their support e-mail: [email protected] ,probably they will accept that this LOT is bad.
Thank you dealseer

 

[dealseer]

Will do.

 

[Hanna Instruments]

If you haven’t already,please report your issue to their support e-mail: [email protected] ,probably they will accept that this LOT is bad.
Thank you dealseer

I compared with 2 more Hanna phosphate checkers HI96713 and HI93713.The were giving 0.04ppm PO4 readouts and HI736 was always giving me zero.For 0.05ppm PO4, HI736 was showing 0.01ppm(3ppb=0.01ppm).So my Hanna HI736 was starting to show phospahtes above 0.05ppm what is not acceptable to me.I was writing to hanna support but no luck,they were sayng that was normal.I am using Hanna 736 checker for long time and this is the second time I had bad LOT,the other bad LOT was H:025 but Hanna sent me another LOT imedeatly than.I know that the reagenses from this batch are not good,I can also tell from my tank.If Hanna can not help me,I am asking if someone has this LOT:H066 please confirm if the readouts are low.
Thank you

Thank you for using our products and for being a valued Hanna customer.

The HI96713 Phosphate Low Range Portable Photometer has an accuracy statement @ 25°C (77°F) of ±0.04 mg/L ±4% of reading.

The HI736 Saltwater Aquarium Ultra Low Range Phosphorus Colorimeter - Checker® HC has an accuracy statement @ 25°C/77°F of ±5 ppb ±5% of reading.
5 ppb Phosphorus is equal to 0.015 ppm PO4.
3ppb Phosphorus is equal to 0.009 ppm PO4.

If you are located outside of the United States its best to use the link below and find the country nearest you and contact the office there for fastest service.

https://hannainst.com/find-my-hanna

Phosphate concentrations can very in a reef tank depending on the time of day you test. Lighting cycles can affect photosynthesis rates of Zooxanthellae, phytoplankton and algae.

A reading on the HI736 of 0.05ppm PO4 would be equal to 17-19 ppb. Is that the reading you got?

I am unsure how you know the lot you have is bad? Observing your aquarium is not indicative of knowing your phosphate concentrations at such low levels. The levels you indicated are all within the accuracy statements of the Checkers and your scenario shows no cause for concern.

Also visit our blog to make sure you are following our 8 checker best practices such as indexing the cuvette in the same position every time, removing any air bubbles, finger prints or smudges and using separate pipettes/syringes for freshwater and saltwater.

 

[vsutarov]

Hanna 736 was giving every time 0ppb and not only on my tank. If it was realy 0 corals would be dead by now many times and I also would not have to clean my glass every 2 days. But that was the reason I got suspicious and compared the readings with my friends hanna 96713 low range phosphate meter and readings are from 0.03-0.05ppm phosphate.And I also compare with redsea low range phosphate pro test and this one also shows some phisphate but hard to tell exactly how much,it is around 0.04ppm. These are the reasons how I found that my LOT is not good for my needs. maybe it would be more acurate for higher cincentrations I can not tell.
I have to tell that I am using 736 meter for years and I am very satisfied with this meter it is very acurate but sometime I receive bad LOT reagenses. I also had bad luck with LOT:025 ,they were giving me higher readings.
I had some conversation emails with hanna support,they were also stating that maby I make mistake when I measure,also stating that readings are not in ppm,talking about acuracy. But I wil also ask you the same question,why dont you check the LOT for yourselve and put here results or somehow demant me about lower readings.I am still waiting the answer.
I am testing my water with my friends 96713 meter every week and must tell that this meter is also a good one. These are only my observations and experiences I dont know about the others. Maybe you will get more observations about this LOT if you still havent by now,we will see.

 

[vsutarov]

I can also record a movie how I make the measurement.

 

[Hanna Instruments]

Hanna 736 was giving every time 0ppb and not only on my tank. If it was realy 0 corals would be dead by now many times and I also would not have to clean my glass every 2 days. But that was the reason I got suspicious and compared the readings with my friends hanna 96713 low range phosphate meter and readings are from 0.03-0.05ppm phosphate.And I also compare with redsea low range phosphate pro test and this one also shows some phisphate but hard to tell exactly how much,it is around 0.04ppm. These are the reasons how I found that my LOT is not good for my needs. maybe it would be more acurate for higher cincentrations I can not tell.
I have to tell that I am using 736 meter for years and I am very satisfied with this meter it is very acurate but sometime I receive bad LOT reagenses. I also had bad luck with LOT:025 ,they were giving me higher readings.
I had some conversation emails with hanna support,they were also stating that maby I make mistake when I measure,also stating that readings are not in ppm,talking about acuracy. But I wil also ask you the same question,why dont you check the LOT for yourselve and put here results or somehow demant me about lower readings.I am still waiting the answer.
I am testing my water with my friends 96713 meter every week and must tell that this meter is also a good one. These are only my observations and experiences I dont know about the others. Maybe you will get more observations about this LOT if you still havent by now,we will see.

There is no problem with the lot HO66.

You can purchase a standard HI736-11 to make sure your Checker is functioning correctly.
HI736-11 Phosphorus Ultra Low Range Checker® HC Calibration Check Set

Since you have had this Checker for 5 years its possible the internal light source can become damaged, not emitting adequate light for absorbance measurements.

Also you have to take into account the variance on the accuracy statements.

If your HI736 read 0 then your reading can be as high as 5ppb.

If your HI96713 read 0.05ppm, your reading can be as low as 0.01ppm.

These two values fall within each other and comparing instruments will have some variance. They are not handled the same and are subject to differences due to user care.

 

[vsutarov]

Thank you for declaring that LOT:066 is fine.
This is producing my other question:I have few readouts on HI96713 from 0.03-0.05ppm and 0ppb readouts made in the same time on HI736. Which one should I consider to be acurate?
I will also buy another pack of HI736 reagents and will compare the readouts with LOT:066 and will post here. I hope I am not going to receive the same LOT [emoji3]

 

[Hanna Instruments]

Thank you for declaring that LOT:066 is fine.
This is producing my other question:I have few readouts on HI96713 from 0.03-0.05ppm and 0ppb readouts made in the same time om HI736. Which one should I consider to be acurate?

Its hard to say as the condition of the instruments is unknown. Age and frequency of use should be taken into account.

That being said the optical system on the HI96713 is more advanced. Also the HI96713 can be calibrated while the Checkers can only be validated with standards.