Fauna Marin phosphate test kit VS Hanna ULR Phosphate checker

[evolutionZ]

Hi everyone, as per thread title, I have a FM phosphate test kit and a recently purchased brand new Hanna HI774 checker with new reagents. Consistently over >5 tests, my FM phosphate test kit produces results of 0.03ppm. However my Hanna HI774 returns consistent result of 0.50ppm, as you can tell the results were vastly different.

So to try and find a solution, i sent a sample of water ( the same sample taken during one of the FM VS Hanna test) for a Reef Factory ICP test and from where i'm located, the test took 2 weeks so i'm not sure if that is a factor to consider. The ICP test shows phosphate of 0.06ppm.

I have been using Hanna checkers for a long time so I know how to use them properly. I always test at the same time of the day and together using the same water sample for both FM and Hanna kits.

What else can I do to try and determine which kit should I trust?

TIA

 

[CasperOe]

That is a very, very big difference! Do you have other reagents you can try? Something's up for sure! The Hanna is really hard to get wrong so I'm sure you're doing it the right way..

Judging by your ICP I'd trust the FM test more, your Hanna checker may be damaged.

I suppose you can bring in a water sample to the LFS and have them verify for you

 

[evolutionZ]

That is a very, very big difference! Do you have other reagents you can try? Something's up for sure! The Hanna is really hard to get wrong so I'm sure you're doing it the right way..

Judging by your ICP I'd trust the FM test more, your Hanna checker may be damaged.

I suppose you can bring in a water sample to the LFS and have them verify for you

Indeed it is! I do have another pack of brand new reagent which I will open up and test with that..

I'm not sure if the Hanna checker is damaged because firstly, its brand new from BRS, secondly I actually purchased a used Hanna HI774 that came with some reagents, and the results were also consistently 0.50 - 0.55. I then thought that checker might be failing and purchase a brand new one instead but results were very similar.

 

[CasperOe]

Indeed it is! I do have another pack of brand new reagent which I will open up and test with that..

I'm not sure if the Hanna checker is damaged because firstly, its brand new from BRS, secondly I actually purchased a used Hanna HI774 that came with some reagents, and the results were also consistently 0.50 - 0.55. I then thought that checker might be failing and purchase a brand new one instead but results were very similar.

So, you have tested with two different Hanna HI774s? And they give you similar readings? Then I'd be inclined to trust that (.. as much as you can trust a Hanna checker!)

Two weeks can be a long time in a reef tank, so that ICP from Reef Factory may very well show your parameters correctly two weeks ago where your dual Hanna checkers show you todays results.

I have never tried the FM tests kits, but I have never found a manual phosphate test kit that I can accurately read. I use the Hanna HI736 for phosphorus and the Reef Factory Smart Tester for trends.

Bring a sample in to your LFS for confirmation.

 

[evolutionZ]

So, you have tested with two different Hanna HI774s? And they give you similar readings? Then I'd be inclined to trust that (.. as much as you can trust a Hanna checker!)

Two weeks can be a long time in a reef tank, so that ICP from Reef Factory may very well show your parameters correctly two weeks ago where your dual Hanna checkers show you todays results.

I have never tried the FM tests kits, but I have never found a manual phosphate test kit that I can accurately read. I use the Hanna HI736 for phosphorus and the Reef Factory Smart Tester for trends.

Bring a sample in to your LFS for confirmation.

Yes I have tested with 2 different HI774s with different reagents and they were of similar readings.

The ICP sample though taken 2 weeks ago, was also tested with both FM and Hanna checkers.

I'm inclined to believe the Hanna as well.. Maybe I can bring my water sample to a LFS for one of those spintouch water tester.

 

[am3gross]

First make sure you are getting the right reagents, I got them confused one time. 2ndly I would recommend getting the phosphorus ULR along with the calibration check set to make sure your device is working correctly. BRS does sell a calibration standard for the HI774 as well, so you could get that to check the devices you already have.

 

[evolutionZ]

First make sure you are getting the right reagents, I got them confused one time. 2ndly I would recommend getting the phosphorus ULR along with the calibration check set to make sure your device is working correctly. BRS does sell a calibration standard for the HI774 as well, so you could get that to check the devices you already have.

Yes the reagents are definitely correct. I might get a calibration standard from BRS for my HI774 then, they are not cheap so ain't getting another checker!

 

[am3gross]

Yes the reagents are definitely correct. I might get a calibration standard from BRS for my HI774 then, they are not cheap so ain't getting another checker

I have found the phosphorus one to be more accurate in my experiences. I have both but have not touched the phosphate one since getting the new one.

 

[DCR]

ICP cannot detect phosphate. They must be using some other photometric or wet method to determine phosphate, so it may not actually be independent. If it is actually 0.5 ppm you should be able to see a slight blue coloration in the vial after adding the reagent. Check the condition of your vials. Anything that affects the ability of light to pass through it will affect the results.

 

[Troylee]

Are you leaving the Hannah flat on a table and holding the button down and letting the 3 min timer count down? Many people including myself held them and it gives out wonky readings.. the Hannah must be placed on a flat surface and not touched while testing for best results. Be nice if the instructions mentioned that… ugh

 

[Pod_01]

ICP cannot detect phosphate. They must be using some other photometric or wet method to determine phosphate,

FM Total ICP test does provide both:

Not sure what is included in OP ICP test.
Also with FM titration test, shaking/mixing is important.

With Hanna I read few times that one can have incorrect reading due to other substances in the water sample.
For example when I used Lanthanum Chloride I had some odd results from Hanna but I don’t have any scientific paper to back this up. It might have been caused by something else or just my incompetence.

 

[evolutionZ]

So I think I can conclude that the Hanna checker is the accurate one. I mixed a new batch of Red Sea salt mix few days ago and was put into storage. Took a sample out today and tested it and the hanna checker shows 0.01ppm.

 

[evolutionZ]

So the first picture below is tested with a fresh red sea salt mix, while the 2nd pic is the vial after testing of my tank water resulting in 0.55ppm. U can clearly see the blue tint, while the fresh salt mix had no tint at all.