Hana ULR Phosphate checker

[griff500]

I have used this for a long time and I can get quite consistent readings with it. I've found that accuracy has not been what I was expecting.

After battling phosphate for a while I got a Red Sea Pro phosphate test kit and it showed a very light initial colour, fading to almost nothing after the 15-minute wait period.

I therefore purchased a reference solution to test the kits and this has 0.08 phosphate in it.

The Red Sea kit gave me exactly 0.08. The Hana kit gave me 0.27. I retested multiple times and got consistent readings from both kits.

So I now have zero phosphate, although some will be used up by the tank, the little bit of algae I have and corals, but that's not what I was aiming for and it's happened due to reliance on a test kit.

I got new cuvettes for the Hana and still got the same consistently high readings, these being far higher than the range of accuracy promised by the test kit. The only thing I haven't tried is new batteries, but I don't see why that would make a difference and the low battery warning has not shown.

Always test your test kits!

 

[Randy Holmes-Farley Verified Community Expert]

What standard?

You correctly converted ppb P into ppm phosphate for the Hanna?

 

[griff500]

What standard?

You correctly converted ppb P into ppm phosphate for the Hanna?

Hi Randy.

If you are asking about the reference solution when you ask 'what standard' then it was the DSR one (from the product range that @glennf has produced). If it doesn't actually contain the stated 0.08 of phosphate then it's a big coincidence that the Red Sea kit showed that level so I'm reasonably confident that it's fairly reliable, unless there are known issues with the Red Sea kit showing 0.08 results for reference kits, but then I would not expect zero for tank water.

I converted by multiplying the reading of 90 by 3 and dividing by 1,000 - not absolutely correct but at that level I couldn't see the point in being absolutely exact. Exact would be 0.28.

Thoughts?

 

[Randy Holmes-Farley Verified Community Expert]

OK, just checking. I have no reason to believe that standard is correct or incorrect.

 

[griff500]

OK, just checking. I have no reason to believe that standard is correct or incorrect.

I wasn't being defensive, if it came across that way - it's not my product.

It's annoying to be fixing a problem that turns out to not exist... again... I think testing your test kits against a reference solution is a good thing to do based on this and previous experience (that I clearly learned nothing from or forgot the lesson).

I had another thread that you helped with where I believed that GFO was making no difference and that belief was based on the Hanna test results. I've ended up stripping the tank of phosphate due to this and I'm not hoping that it rises with increased feeding rather than dosing some phosphate, which might be a better approach?

 

[MnFish1]

I wasn't being defensive, if it came across that way - it's not my product.

It's annoying to be fixing a problem that turns out to not exist... again... I think testing your test kits against a reference solution is a good thing to do based on this and previous experience (that I clearly learned nothing from or forgot the lesson).

I had another thread that you helped with where I believed that GFO was making no difference and that belief was based on the Hanna test results. I've ended up stripping the tank of phosphate due to this and I'm not hoping that it rises with increased feeding rather than dosing some phosphate, which might be a better approach?

Was the standard water with phosphate in it or was it ‘sea water ‘with all of the other things in it but a standard phosphate level

 

[MnFish1]

Also no offense but are you doing the Hanna test correctly? Many people do not follow the insteuctions

 

[recess62]

Another thing you need to take into consideration is the temperature of the standard when using it to check the accuracy of the unit. When I first used mine I did not warm it up and my checker was way off. After warming up the standard to 25 c my checker was spot on

 

[griff500]

Was the standard water with phosphate in it or was it ‘sea water ‘with all of the other things in it but a standard phosphate level

The reference solution was not sea water - it is a reference solution bought from a shop, detailed in a previous post. It states that it contains 0.08 phosphate - the Red Sea test showed 0.08. The Hanna test showed around 0.27. I tested multiple times with each kit and got the same readings each time.

 

[griff500]

Another thing you need to take into consideration is the temperature of the standard when using it to check the accuracy of the unit. When I first used mine I did not warm it up and my checker was way off. After warming up the standard to 25 c my checker was spot on

I can float it in the tank for a while and give that a go, although it was at room temperature and the room isn't exactly cold recently. Worth a try, although it's odd that the Red Sea test kit gave exactly what I expected and the Hanna kit was SO far off the mark at 0.27. I'll try it nonetheless and report back.

 

[griff500]

Also no offense but are you doing the Hanna test correctly? Many people do not follow the insteuctions

Yes, I'm doing it absolutely correctly and getting consistent results - just nowhere near correct it would seem.

 

[recess62]

I can float it in the tank for a while and give that a go, although it was at room temperature and the room isn't exactly cold recently. Worth a try, although it's odd that the Red Sea test kit gave exactly what I expected and the Hanna kit was SO far off the mark at 0.27. I'll try it nonetheless and report back.

I used the Hanna standard. I put it in my sump for a few minutes

 

[griff500]

Reference solution (0.08) in my sump for an hour.

Red Sea kit - 0.08

Hanna kit - 48 (0.15)

 

[MnFish1]

The reference solution was not sea water - it is a reference solution bought from a shop, detailed in a previous post. It states that it contains 0.08 phosphate - the Red Sea test showed 0.08. The Hanna test showed around 0.27. I tested multiple times with each kit and got the same readings each time.

Right- but hanna checker is not designed to test phosphate in fresh water.... My guess is that the pH,etc has to be in a certain range.

 

[griff500]

Right- but hanna checker is not designed to test phosphate in fresh water.... My guess is that the pH,etc has to be in a certain range.

It’s not freshwater – it’s a reference solution.

 

[Randy Holmes-Farley Verified Community Expert]

It’s not freshwater – it’s a reference solution.

I'm not suggesting yours is freshwater, but a phosphate "reference solution" could be made in freshwater.

 

[griff500]

I'm not suggesting yours is freshwater, but a phosphate "reference solution" could be made in freshwater.

A reference solution surely has the constituents of seawater as far as required for a test to be as accurate as possible with hobby test kits:

Saltwater reference solution (11/2017).
Sal: 33ppt / KH/Alk=9dKH / Ca=435 / Mg=1340 / K=395 / Sr=8 / B=4 / I=0,08 / PO4=0,08 / NO3= (2) / (PH8,1 Non-buffered).

I don't believe that is going to give a false reading based on a 'freshwater' base any more than saltwater mixed from RODI will give a false reading.

Don't forget that the Hanna kit gives a significantly higher reading that the Red Sea kit for the reference solution and for my tank water and the effluent from the reactor.

 

[Gablami]

It’s coincidental that my friend and I are exploring the same problem.

I have also felt that my Hanna kit has been giving me inconsistent and higher readings than I would expect. My friend has been getting a phosphate Hanna reading of 90 and a Red Sea pro reading of 0.

This is from my tank yesterday.

A ten-fold difference.

Red Sea uses a two step process, with sulfuric acid/ammonium molybdate as a first step and tin chloride as a second step.

Hanna used a single step, potassium disulfate.

I found this article helpful “Understanding the different phosphorus tests”: https://www.hach.com/asset-get.download.jsa?id=50989301315

We have emailed Red Sea and Hanna to inquire what forms of phosphate their test will detect. Maybe all together we can get it the bottom of this!

(Credit to @RandyC who did most of this leg work...I’m just tagging along for the ride)

 

[Randy Holmes-Farley Verified Community Expert]

A reference solution surely has the constituents of seawater as far as required for a test to be as accurate as possible with hobby test kits:

Saltwater reference solution (11/2017).
Sal: 33ppt / KH/Alk=9dKH / Ca=435 / Mg=1340 / K=395 / Sr=8 / B=4 / I=0,08 / PO4=0,08 / NO3= (2) / (PH8,1 Non-buffered).

I don't believe that is going to give a false reading based on a 'freshwater' base any more than saltwater mixed from RODI will give a false reading.

Don't forget that the Hanna kit gives a significantly higher reading that the Red Sea kit for the reference solution and for my tank water and the effluent from the reactor.

That's a fine reference solution if it has those properties and if it is stable.

But it was an appropriate question for MnFish to ask since we use many reference solutions that are not seawater mimics and one should not assume they are unless they say so.

 

[griff500]

That's a fine reference solution if it has those properties and if it is stable.

But it was an appropriate question for MnFish to ask since we use many reference solutions that are not seawater mimics and one should not assume they are unless they say so.

Absolutely, and I don't believe I questioned his, erm, question. I have confidence in the reference solution.

The post above yours is interesting and it looks like I am not alone.