Fe: Are there hobbyist kits availabile that measure this accurately?

GR1KTR

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It's been a while since I stopped measuring dissolved Fe, as I was told long ago that the test kits available to the average hobbyist are far from accurate.

Has this changed? Are there kits available now that do measure accurately, outside of lab grade equipment?
 

Asmack Arabia

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i use the hanna iron colorimeter and so far, so good. i think. i haven't really tested its accuracy against a reference solution. but i like the idea that it gives me digital result rather than entrusting the result to my eyes for the color changes.
 

GR1KTR

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UDGags;122476 said:
It really depends on the type of iron you dose I believe.

EDTA Chelated Iron (13%) is what I use. What type/s of Fe are suitable for testing using hobby kits?
 

Tom Barr

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You need to match the ppm dosed vs the relative rate of growth, then also consider how much of the Fe is actually in the dry weight of the plant.
This has very rarely been done for aquatic plants, and only for EDTA Fe. I think folks can best do this by eye balling it and trying to have everything else done well before they can arrive at a dosing rate.

I'm not sure what we test and when are really that representative of what is happening.
Same with other nutrients also. Targets are useful to dose or upper bounds, or non limiting ppm's for most general conditions.
Test kits did little to achieve those ranges however. Mostly eyeballing.

Then they tested.........and Fe is hard due to rate of which is can persist in the aquarium........or not.
 

GR1KTR

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You need to match the ppm dosed vs the relative rate of growth, then also consider how much of the Fe is actually in the dry weight of the plant.

Is there a direct relationship between the level of Fe in the dry weight of the plant, and it's uptake/requirement for Fe in the water column? Or do they just store it better in comparison? Or both?

This has very rarely been done for aquatic plants, and only for EDTA Fe.

I'd love to find this study. Any hints/tips for tracking it down? Sounds like an interesting read..
 

Jeffrey Funk

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UDGags;122476 said:
It really depends on the type of iron you dose I believe.

My experience with Fe analysis by ICP-OES is that [Fe] in the water column does depend upon the type of Fe chelate dosed. People that dose Fe(EDTA) often have measurable Fe in their aquarium water (>0.01 ppm) while those people who dose Fe(Gluconate) often times have much lower measurable Fe in the aquarium water, even if they dose the same amount during each time.

Because of this, it's not always clear that a low [Fe] in the aquarium means that you are not dosing the correct amount of Fe. You really need to watch your plants and see how they are growing...
 

reef12

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I use Sea Chem and says between 0.1 and 0.2.

Don't know if correct but everything looks alright.

Any help.


Jeff
 

Tom Barr

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Jeffrey Funk;122509 said:
My experience with Fe analysis by ICP-OES is that [Fe] in the water column does depend upon the type of Fe chelate dosed. People that dose Fe(EDTA) often have measurable Fe in their aquarium water (>0.01 ppm) while those people who dose Fe(Gluconate) often times have much lower measurable Fe in the aquarium water, even if they dose the same amount during each time.

Because of this, it's not always clear that a low [Fe] in the aquarium means that you are not dosing the correct amount of Fe. You really need to watch your plants and see how they are growing...

Adding even more to this quagmire, we have variation in the alkalinities from user to user.
This makes the chelators behave differently.

Fe Gluconate will act differently in my low KH of 20 ppm vs another user who's KH is 140 ppm.
DTPA seems pretty stable over the pH/KH ranges we often see.

I think overall, we are left with dosing and know amount and chelator type and then observations of the plant's growth, color, sheen, form.
Amount (mass) and chelator types offer a known standard baseline to compare.

If you choose an upper bound, say a very high light tank, plain sand to remove any sediment sources, CO2 rich, faster growing stems(a wide variety of species), non limiting feerts, good algae eaters, water changes daily or often, then you could see what an upper target would be.
From there, pretty everyone would dose LESS.

This way we'd have an upper bound, and then the lower is obviously no trace dosing of Fe at all.
Everything else should fall in between that.

My 120 is a pretty good canary in the coal mine for this, but I have ADA AS which is rice paddy soil pretty rich in Fe.
If I had plain sand, then it would be ideal.
But I have in the past.

Plant growth studies suggest an order of magnitude higher than what I dose, but I was never sure what Bill Haller did as far as frequency. I could ask him if he has not retired in the near future.
I'm adding about 1-2 ppm a week total.

I add a mix of chelators, the Gluconate, DTPA and the ETDA and my KH is low.
The differences are subtle for nice plant health responses for Traces.

Sheen on the leaves is the biggest indicator I look for.
Daily seems to do a little better than 2x a week for many stem plants, but less so for others.
 

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reef12;122525 said:
I use Sea Chem and says between 0.1 and 0.2.

Don't know if correct but everything looks alright.

Any help.


Jeff

That's from Paul Sears et al, back in the mid 1990's, they assumed more would lead to hair algae and thread algae.
Greg Morin use to discuss with us back then, but he mostly went along with us and then suggested a more conservative approach(so did Tropica for that matter) for generla instructiosn for dosing, sicne many have only a few plants, so they all error on that lower range.
 

GR1KTR

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Tom Barr

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I would heed what Jeffery stated as well. Most will offer similar advice that are in the know.
 

GR1KTR

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Why do you use EDTA, Gluconate and DTPA in your mixture, Tom? I would have thought that one may be enough?
 

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GR1KTR;122640 said:
Why do you use EDTA, Gluconate and DTPA in your mixture, Tom? I would have thought that one may be enough?

Cause I feel sexy:)

Mostly because one is very easy for plant uptake, but last only a few minutes perhaps, then the other is moderate and then the DTPA will hang out for a couple of days.
My water is soft. KH is about 20 to maybe 35-37 ppm. If I had say 100 + ppm KH, I might only use DTPA and the Plantex.