Digital Iron testers - anyone?

[MichaelJ]

Hello, I am just a little curious about monitoring my Iron levels from the time of dosing my micros and onwards to see if I can infer anything about the rate of uptake. I am looking at this one from Hanna Instruments.
I am not super excited about the fairly low accuracy (-/+ 0.04ppm) on this or the similar product from Milwaukee Instruments. Are anyone using a Digital Iron tester they can recommend?

Cheers,
Michael

 

[hypnogogia]

Just looked at that Milwaukee Instruments one - it’s always great when the accuracy range is greater than the resolution! 😂

 

[MichaelJ]

Just looked at that Milwaukee Instruments one - it’s always great when the accuracy range is greater than the resolution! 😂

Right! but hey, its digital and got two decimal places!

Cheers,
Michael

 

[dw1305]

Hi all,

I am just a little curious about monitoring my Iron levels from the time of dosing my micros and onwards to see if I can infer anything about the rate of uptake

I think it is a really tricky one. You would think it should be easy, because iron ions readily form coloured insoluble compounds, and in some ways it is, but growers actually tend to use leaf colour as the indicator of iron status, it is back to <"the plants can't lie"> argument.

The problem is mainly that test kits won't tell you how much of that iron is plant available, because the testing methods <"all either aim to reduce the iron oxides"> and complexes to ferrous (Fe++) ions.

.... A decomplexing/ reducing agent breaks down weakly complexed forms of iron and converts ferric iron to ferrous iron. The ferrous iron reacts with PPST to form a pink colour.......

or oxidise the ferrous (Fe++) compounds to ferric (Fe+++) oxides ("rust"). I think the Hanna one uses oxidation via the <"TPTZ method">. The same problems also inhibit the use of <"analytical kit like ICP & MP-AES"> etc for iron, you will get an accurate figure for total iron content of the water, but you won't know if it is plant available. It is back to <"the brick problem">.

it’s always great when the accuracy range is greater than the resolution!

Right! but hey, its digital and got two decimal places!

It's a <"1970s stereo">.

cheers Darrel

 

[palcente]

Not a digital solution, but if you are looking for a plant that would reliably indicate water column iron presence or lack of it, that would be hygrophila tripartita. Trick is to plant it out of the substrate and in low iron scenario the new growth will be very visibly lighter when you look at it from the top. It grows really fast so you get your daily reading that is if your amano shrimps do not decimate it overnight!

 

[MichaelJ]

The problem is mainly that test kits won't tell you how much of that iron is plant available, because the testing methods <"all either aim to reduce the iron oxides"> and complexes to ferrous (Fe++) ions.

Thanks Darrel. Another tricky bit of course is that I dose such a small amounts that measuring whatever is in the water column will be unreliable at best and after a few days it will probably just be what is not plant available anyway.

Not a digital solution, but if you are looking for a plant that would reliably indicate water column iron presence or lack of it, that would be hygrophila tripartita. Trick is to plant it out of the substrate and in low iron scenario the new growth will be very visibly lighter when you look at it from the top. It grows really fast so you get your daily reading that is if your amano shrimps do not decimate it overnight!

Thanks @palcente, Yes. I like this idea. I think my plants gets enough iron, I was just curious if I could get some sort of bearing on the uptake over time.

Cheers,
Michael