Fe uptake and active Fe in plants

[Tom Barr]

I generally do not address inorganic water reactions with Fe, but we do know pH.KH affect Fe and the type of chelator....and the concentration, frequency etc can all play roles, there are many different precipitations that can occur.

To address the issue, I look more at plants, rather than residuals in the water column.

Basiouny et al (1977) did some good work with a submersed macrophyte and Fe chelated.

ScienceDirect - Aquatic Botany : Absorption of iron and growth of Hydrilla verticillata (L.F.) Royle

A very good paper on Fe and aquatic plants:
http://www.apms.org/japm/vol27/v27p65.pdf

Active Fe, a "Fe pool" if you will... seems to play a role.

Both Gerloff and the above citations show clearly that higher levels are taken up and optimal, reduce stress impacts(chemical and physical). Why do so many suggest 0.1ppm then?

I wonder because they do not justify this.
PMDD suggested residual mostly from a hypothesis(it has been falsified over a decade ago) that stated that thread and hair algae may appear when Fe was too high.

Gerloff suggested using 1/5th Hoagland's which gives 42 N to 0.4ppm of Fe or 100:1 ratio. PMDD scaled this down to 10ppm of NO3 and 0.1ppm of Fe.
However, Gerloff did not look at Fe specifically..........big difference.

If you have higher levels of light, CO2 or NO3 etc, then you would scale it up appropriately if you used the ratios from Gerloff/Hoagland. Still, they are not anywhere as specific as the other cited references above.



Regards,
Tom Barr

 

[Philosophos]

What are your own experiences with this sort of thing Tom? Have you pushed it to 7.55-8ppm in any tanks? Is there anything else that needs to change accordingly?

-Philosophos

 

[Tom Barr]

What are your own experiences with this sort of thing Tom? Have you pushed it to 7.55-8ppm in any tanks? Is there anything else that needs to change accordingly?

-Philosophos

I've gone to 2ppm, using TMG.
I've gone to 200mls in 75 liters of flourish

Never really added these upper ranges personally.
But...........I think the research suggest that adding much more than the 0.1ppm suggestions is bit lacking, we likely should be adding a lot more, particularly with healthy growth and higher light.

Hard to say what is optimal for a planted tank.
I have a spiked Fe trace I custom made, so it's extremely rich, 1-2ppm is a common dosage for me.



Regards,
Tom Barr

 

[Philosophos]

I've got a bag of Fe-DPTA sitting around doing nothing. I think I'll try supplementing the CSM+B and hitting 1-2ppm next time I need to re-mix trace.

Beyond having more nutrient stores/better resilience, have you noticed any other differences at higher iron levels? Appearances, growth rates, etc?

-Philosophos

 

[Tom Barr]

It's an overall growth thing, the sheen on many species looks waxier, healthier.
Plants seem to thrive more, more pearling.

I think once fear is replaced with actual good dosing/testing, then you can add more and see.

It's an eyeball thing.

I think many have been told that excess Fe will lead to algae, thread and string algae etc..........this is false.

Plants will still grow with less, but you get better results if the other parameters are in good shape.

It's not about doing the min to get by, it's about what is optimal for the plants.


Regards,
Tom Barr

 

[Biollante]

US 2 Cents

My US 2 cents worth.

I have been dosing higher iron for some time and have seen, purely subjectively, what appears to be substantial improvement, appearance and propagation anyway of my substantial plants.

For the record, I have experienced no alga outbreak, of any cause.

Without some related increase in Manganese, I am not sure how much extra benefit is derived from the extra iron.

I dose heavy and I get labeled a ‘nutrient type,’ really I believe in high CO2, I have been aiming for 40 ppm, discovered it was more like 33 ppm, which makes one wonder; I believe in good water quality, extra filtration and good circulation.

My goal is simply not to limit growth while providing optimum conditions for all fauna and flora in my care.

Iron is good, as with more CO2, more other stuff to optimize the growth.

Biollante

 

[Philosophos]

As one of the studies said, the requirement for Mn decreases proportionately as iron increases. I wonder why.

I'll definitely be going up with the iron. I kept .6ppm more for the fact that I didn't know higher levels had any point. I guess this is why you made the post though, and I'm glad you did.

I also always thought there might be something up with toxicity to fauna. After some reading on the EPA Ecotox database, my opinion quickly changed.

Anyone who doesn't have a link to this site really should have it bookmarked: EPA: Welcome to ECOTOX )

-Philosophos

 

[Biollante]

Just Cuz

When I first started to comprehend Liebig's Law of the Minimum, my first concern was that I was inevitable and invariably induce an algal bloom the likes of which the world had never seen and that I was going to kill my critters.

I guess my point is that I am not very concerned about the minimum I can get away with. For me it is being sure that everything that is necessary is there. Stopping short of toxicity.

I think back how silly I was about advancing the iron beyond 0.1 ppm, good grief. All I could think was ‘toxicity’! I’ll kill all my critters’ now I read Tom Barr at 200 ppm, sheesh.

I will hope that before I get a chance to give you my thoughts on the manganese, iron relationship, I will hope someone who actually might know will have answered so I can say, “What he said!”

My guess is that magnesium is (allegorically speaking) like a catalyst and the farther into the reaction the less is required. I suspect (don’t know, can’t cite) that it may be an ion competition thing.

Anyway later,

Biollante

 

[Tom Barr]

As one of the studies said, the requirement for Mn decreases proportionately as iron increases. I wonder why.

I'll definitely be going up with the iron. I kept .6ppm more for the fact that I didn't know higher levels had any point. I guess this is why you made the post though, and I'm glad you did.

I also always thought there might be something up with toxicity to fauna. After some reading on the EPA Ecotox database, my opinion quickly changed.

Anyone who doesn't have a link to this site really should have it bookmarked: EPA: Welcome to ECOTOX )

-Philosophos

For Ecotox issues, I typically chose Daphnia and other inverts as they tend to be the most sensitive. CRS's are models because they are easy to breed and highly inbred, so little genetic variation between individuals, and hyper sensitivity.

So if they make it, it's safe to assume most other fish certainly will also.

Regards,
Tom Barr

 

[Tom Barr]

I will address Mn later.


regards,
Tom Barr

 

[Solcielo lawrencia]

I asked Easy Life about iron toxicity and this is their response:
"Too high dosages of iron in the water, can turn out to be problematic. Plants will certainly react negatively, so the iron content should not be exaggerated. The iron content should not exceed about 3 ppm Fe, it's even toxic to plants at about 5 ppm Fe."

Is that toxicity due to competitive inhibition, preventing other nutrients from uptake?

 

[Tom Barr]

No, I have a strong feeling that is hogwash, the research says 6-8 ppm for Hydrilla, which will die back pretty easily if there's toxic levels of metals(eg, Copper).
1ppm will kill Hydrilla for copper.

Who the heck adds 3 ppm of Fe?

That is 10X more than anyone might try per dose.
Your water will look yellow. It's not even really a reasonable upper bound, it's like adding 100-300 ppm of NO3.

 

[Tom Barr]

No, I have a strong feeling that is hogwash, the research says 6-8 ppm for Hydrilla, which will die back pretty easily if there's toxic levels of metals(eg, Copper).
1ppm will kill Hydrilla for copper.

Who the heck adds 3 ppm of Fe?

That is 10X more than anyone might try per dose.
Your water will look yellow. It's not even really a reasonable upper bound, it's like adding 100-300 ppm of NO3.

 

[Solcielo lawrencia]

Who the heck adds 3 ppm of Fe?

*Raises hand* It was an accident and the water did turn yellow.

 

[Tom Barr]

*Raises hand* It was an accident and the water did turn yellow.

*Raises hand also*, 200mls of SeaChem into 20 gallons of tank.
Accident? Yep.

How we learn.........

 

[Tom Barr]

*Raises hand* It was an accident and the water did turn yellow.

*Raises hand also*, 200mls of SeaChem into 20 gallons of tank.
Accident? Yep.

How we learn.........

 

[Solcielo lawrencia]

*Raises hand also*, 200mls of SeaChem into 20 gallons of tank.
Accident? Yep.

200!!!??? Was it an accidental spill or accidentally intentional?

 

[Tom Barr]

Dosing pump was not checked prior to leaving a client's place.
Dumped the whole thing in all at once.

I do systems checks before I leave now.

 

[Tom Barr]

Dosing pump was not checked prior to leaving a client's place.
Dumped the whole thing in all at once.

I do systems checks before I leave now.

 

[hbosman]

So, I take it that there's no reason to go above .3 ppm? I currently dose .25 ppm daily from CSM+B and DTPA.