Lets talk about iron and micros. Experts only. - The Planted Tank Forum
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post #1 of 37 (permalink) Old 01-08-2005, 05:53 PM Thread Starter
 
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Lets talk about iron and micros. Experts only.

I want to start a discussion about iron and micro dosing. The goal here is to get some real data about what works and what doesn't. It's my hope that we can come up with some real hard solutions to this perplexing little "mystery".

I know I'm not the only one that feels like theres no real substance to micro dosing.

Macros for the most part have been real simple. 10ppm nitrates, 1ppm phosphate, 10-30ppm potassium, simple right. Maintain a 10-1 ratio of nitrate to phosphate and alls well. Plus there's lots of room to experiment with fairly quick consequences when deviating from these parameters, which makes it fairly easy to determine cause and effect. Not so with micros. It can take weeks for plants to respond to micros.

Here's some thoughts or questions we might want to discuss:

Are iron tests really useless?
What about the Lamotte/Hach iron tests.
Do we need more iron than Plantex CSM+B offers? If so how much more?
Anyone using Iron Chelate 10% from GregWatson.com? If so, Whats your experience?
Whats your experience for dosing maximum color?
How much is too much micros?
Any other thoughts that would be relevant are also welcome.

I'd like to confine this discussion to planted tank enthusiasts who have something to offer in the way of real experience in this area.

Please don't post general questions about micro dosing in this thread.

Let the discussion begin.
Marcel
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post #2 of 37 (permalink) Old 01-09-2005, 01:39 AM
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Wow - this fits in really well with something I've been considering.

I'm an analytical chemist. I teach at a college. I have the ability to test for K and Fe (and many of the other micros) using our instruments. I already do some consulting and have been thinking about offering my services here. The problem is, I need to be paid something - to cover chemical costs and my time. Maybe this is the way I can get started. I think many people might want to test the micros (at least Fe) when they have trouble. If you want to set up some kind of a longer-term study, maybe we could arrange something.

I agree - the iron test kits are designed to be read by a colorimeter - much more sensitive than the eye. You can put a color chart with it, but you won't get near the sensitivity of a colorimeter. I would analyze it with our Atomic Absorption instrument - orders of magnitude more sensitive than the colorimeter as well - and you don't have to react it first!

The potassium tests are even worse - TURBIDITY - not color! Nearly impossible to tell low levels without a turbidimeter!

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post #3 of 37 (permalink) Old 01-09-2005, 02:03 AM Thread Starter
 
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Well Kevin, I think the first order of business would be to determine the validity of hobby test kits versus the high tech testing methods you have access to. What kinda of costs are we talking about here? Do you have any specific knowledge of chelates vs free iron. Do they measure up equally? For instance, My experience with chelated iron has been 2-3 hours of waiting time for results rather than 45 minutes reccomended on the Seachem kit.

Please forgive my limited chemistry knowledge.

Marcel
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post #4 of 37 (permalink) Old 01-09-2005, 04:21 AM
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Marcel

I am game for a dosing discussion. A christmas master test kit <Red Sea> proved that my water chemistry is a bit off. I have been dosing solid PMDD <ECO Enterprises> for two weeks and hardness <KH>. I am starting slow and documenting changes as I go along. I need to go compressed CO2 next followed by macros...

And any thread needs yet another Chemist!

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post #5 of 37 (permalink) Old 01-09-2005, 08:39 PM
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Quote:
Originally Posted by m.lemay
Well Kevin, I think the first order of business would be to determine the validity of hobby test kits versus the high tech testing methods you have access to. What kinda of costs are we talking about here? Do you have any specific knowledge of chelates vs free iron. Do they measure up equally? For instance, My experience with chelated iron has been 2-3 hours of waiting time for results rather than 45 minutes reccomended on the Seachem kit.

Please forgive my limited chemistry knowledge.

Marcel
Marcel:

I believe the kits are good for what they are - extremely cheap ways to find an approximate answer. In the case of the atomic absorption (AA) instrument, the instrument alone costs $15000. Add in standard solutions and appropriate element-specific lamps, and on a per-test basis it will never compare in terms of cost. However, it is possible to measure in the parts per Billion range for many elements!

Before you posted I had been playing around with a pricing schedule to offer - something like $25 for the first element test with one water sample. $5 per additional sample and $10 per additional element. So a test for potassium and iron on both a tank and a tapwater sample would cost $45. If you are more interested in a long-term study of some sort, I can be very flexible. If there is a possibility of publication in a peer-reviewed journal, I might do it for free.

In terms of chelated iron vs. free iron, it makes sense that the test kit would take a lot longer - when the iron is chelated, it is in a way protected from reactions with other things. In the AA, the sample is aspirated into a flame, so the iron is quickly separated from the chelate and the test result would be the same as for free iron.

A related question I have: Calcium, magnesium, AND iron can be chelated. If you add chelated iron to your tank, can the calcium displace the iron (since there is a lot more calcium in the water), resulting in free iron and chelated calcium (and leaving the iron free to be oxidized)? If this is the case, then there is no point in using chelated iron - it would be a waste of money. I can partly answer this question by looking up the stability constants for iron and calcium chelates, but the concentration difference adds another dimension.

Kevin

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post #6 of 37 (permalink) Old 01-10-2005, 02:43 AM
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I have to admit I am out of my element here with only a rudimentary grasp of water chemistry and a general 2-semester Chemistry background from my Mechanical Engineering curriculum. That being said, I think the results of this type of controlled experiment are definitely publishable. I don't know about some others, but if we could get a bunch of people to pitch in $5, $10, $20, it should cover expenses, and we can ask Kevin to donate his time

I will offer some general experience - the iron found in Plantex CSM+B has not been adequate in my 4wpg, 25ppm CO2 environment. Stem plants show general symptoms of iron chlorosis. I haven't tried the chelated iron from gragwatson, but I may have to soon enough since Flourish Iron is getting expensive.

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post #7 of 37 (permalink) Old 01-10-2005, 02:50 AM Thread Starter
 
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Kevin:
Having you test my water every time I want to know what my iron levels in the aquarium is economically prohibitive.

My thoughts were to have you test a sample with the AA machine and I'll test a sample from the same water with a SeaChem and a Lamottes test kit. This will afford us a basis as to the validity of these kits for aquarium usage.

When iron is freshly added to the aquarium my Seachem iron test kit will readily hand over results. But after 24 hrs the iron seems to have disappeared. What happened to it? Did it precipitate out of the water column and fall to the substrate, did the plants use it up, or has it become some form of iron undetectable by the kits that are commercially available? It's my suspicion that it precipitates and goes into the substrate to be reformed into some form of usable iron as needed in the plants. Perhaps the plants themselves convert it. Flourish Iron is in the form of iron gluconate which I think is a sugar (maybe an amino acid).Correct me if I'm wrong.

I have not acquired a lamotte iron kit yet, so I don't know if it's any better or not. I will go ahead and purchase an iron kit from Lamottes to see if it yields different results than the less expensive SeaChem kit. If the results trurn out to be radically different, then further testing will be necesary with perhaps longer soaking times.

I'm not sure how the Lamotte kit works. It would seem that to get a total iron count, a way to first break down the chelate bond would be necesary before total iron can be extrapolated.

So you see, there are quite a few variables including the premise that you brought up about calcium, magnesium and iron cross chelating.

Maybe, this whole premise about optimum levels of iron in the water column are bogus, maybe the substrate holds the key.

Marcel
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post #8 of 37 (permalink) Old 01-10-2005, 03:03 AM Thread Starter
 
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Quote:
Originally Posted by GulfCoastAquarian
I have to admit I am out of my element here with only a rudimentary grasp of water chemistry and a general 2-semester Chemistry background from my Mechanical Engineering curriculum. That being said, I think the results of this type of controlled experiment are definitely publishable. I don't know about some others, but if we could get a bunch of people to pitch in $5, $10, $20, it should cover expenses, and we can ask Kevin to donate his time

I will offer some general experience - the iron found in Plantex CSM+B has not been adequate in my 4wpg, 25ppm CO2 environment. Stem plants show general symptoms of iron chlorosis. I haven't tried the chelated iron from gragwatson, but I may have to soon enough since Flourish Iron is getting expensive.
I agree that this kind of research is publishable. I know for a fact that this would be very valuable info for planted aquarists and probably those who study planted wet environments, as well as those involved in hydroponic gardening. I suppose it all depends on who you call your peer group.

I like the idea of people pitching in to help out with the cost of this type of research.

Marcel
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post #9 of 37 (permalink) Old 01-10-2005, 02:42 PM
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OK, I'll reply to several things at once here:

1. Yes, the cost is prohibitive for constant monitoring. That's one of the reasons I haven't been jumping up and down in the Swap and Shop section trying to get people to send me water samples. The number of people who would benefit from this type of testing is very small - those who understand enough about the plants and chemistry to know that a trace element is missing, and those who want to verify their test kits (and/or their water company report). The cost, however, is not unjustified - a certified iron standard solution would cost $64.54 + shipping for 100ml (Fisher Scientific). In terms of time, I would need to dilute this to several different concentrations to obtain a calibration curve, then set up and run them and the unknowns on the instrument - assume at least 1/2 hour per element. The standard rates for chemistry Ph.D. consultants range from $75/hour to more than $200. I typically get the $75 end, and I know one other professor here who has done expert witness testimony for $125/hr.

2. In terms of publication, this is where it gets easier for me to ignore everything in #1. In order to get promoted, I have to (among other things) produce peer-reviewed publications. This generally means an article in the chemistry journal literature - I recently published in the Journal of Undergraduate Chemistry Reserach and in Chemical Educator. What I was thinking was someone who is a biologist (aquatic plants) might spearhead this to answer something like your last question - "How much is too much micros?" or "What happens to free ferrous iron in the water column?" and publish in a biological journal. In that case I would be happy to run as many samples as needed to produce the article. It is not totally useless to me if published in the hobby (aquarium) literature, but it won't get me promoted by itself so donating my time is less likely.

3. Current Iron tests: With iron there is the issue of ferrous (Fe+2) and ferric (Fe+3) forms. In addition, we might worry that chelated iron won't respond to the tests. In Standard Methods for the Analysis of Water and Wastewater, 18th edition (1992), three approved methods are provided: the first is AA (as I mentioned using), the second is ICP - an even more expensive instrument, and the third is the phenanthroline method. The phenanthroline method is specific to the ferrous (Fe+2) ion (the other two give total iron) and is generally used in the 0.020 to 5.00ppm range when a spectrophotometer is used to read the color. This is one of the commercial tests sold by Hach (#26672-00). There are several other methods for measuring ferrous and/or total iron - using reagents such as ferrozine, TPTZ, bathophenanthroline. There is even a chemiluminescence method that can detect as little as 5ng/L (5 parts per trillion) of Fe+2! The LaMotte DC1200 uses the phenanthroline, while several of their other kits use bipyridyl (similar to phenanthroline).

4. Iron gluconate - this is a complex between iron (+2) and gluconic acid - which is glucose in which the aldehyde group is oxidized to a carboxylic acid. My reference says the oxidation of glucose to gluconic acid is done commercially by fermentation using an Aspergillus or Acetobacter, or Penicillium organism.

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post #10 of 37 (permalink) Old 01-11-2005, 12:14 AM
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Kevin:

You might want to get ahold of:

Ion chromatography as an alternative to standard methods for analysis of macro-nutrients in Mehlich 1 extracts of unfertilized forest soils
Fischer,
COMMUNICATIONS IN SOIL SCIENCE AND PLANT ANALYSIS. 2004. Vol. 35, Iss. 15-16; pg. 2191 - 2208

Grunt work... Thats what grad students are for right?

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post #11 of 37 (permalink) Old 01-11-2005, 02:06 AM
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This might be useful http://home.infinet.net/teban/iron/ironw.html

Well, at least my algae is pearling...
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post #12 of 37 (permalink) Old 01-11-2005, 03:39 AM Thread Starter
 
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zapus: Thats a great article, chock full of info. Some of it is over my head but definitely worth readind for those who are so inclined.

What I'm getting from it in an over simplified way is this: Calcium seems to reduce the availability of iron, but if I understand it correctly, its mainly because of calciums action of raising the ph of the soil which inhibits irons ability to form chelate bonds with simple protiens. Lower the ph and iron becomes more available. I wouldn't go out and rush to lowering my ph just yet though since I just skimmed the article. I need to read into it a little more.

Maybe Kevin can read it to see what he thinks since he's the chemistry dude. LOL
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post #13 of 37 (permalink) Old 01-11-2005, 01:42 PM
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Quote:
Originally Posted by BlueRam
Kevin:

You might want to get ahold of:

Ion chromatography as an alternative to standard methods for analysis of macro-nutrients in Mehlich 1 extracts of unfertilized forest soils
Fischer,
COMMUNICATIONS IN SOIL SCIENCE AND PLANT ANALYSIS. 2004. Vol. 35, Iss. 15-16; pg. 2191 - 2208

Grunt work... Thats what grad students are for right?
We have a donated ion-chromatography system, but it is in a state of disrepair and we are having trouble getting the manufacturer to help out. It is an attractive option though - especially for things like nitrate and phosphate!

Grad students - we don't have any here (unless you count MBA students and Biology Education MS students). The Citadel is undergraduate only in chemistry. If you want the experiments to take 10x longer with less reliable results, sure - we'll put some undergrads on it It is still nice to pay them or give them some course credit. Both of the papers I mentioned earlier had undergraduate student coauthors.

Zapus: The article you posted has some interesting info. One of the things that strikes me is that terrestrial plants can and do use Fe+3 - is the same true for aquatic root-feeders? This would explain why fluorite is so useful - the roots can abstract the Fe+3 from it! I wonder then about stem plants - since much of their intake is NOT from substrate bound roots, do they require Fe+2 or do they use one of the mechanisms mentioned? Another interesting point is that chelated iron is stated to be ineffective for soil enhancement - is the same true then for aquatics?

Marcel: Your conclusion is true about most metals - the higher the pH, the less soluble - most metals form insoluble metal-hydroxides. This is both good and bad - for instance, aluminum can be toxic to plants. In normal soils, it is insoluble. When the soil is acidified, the aluminium becomes soluble and is taken up by the plant roots - killing it (one of the effects of acid rain).

Kevin

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post #14 of 37 (permalink) Old 01-11-2005, 01:47 PM
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Quote:
Originally Posted by BlueRam
Kevin:

You might want to get ahold of:

Ion chromatography as an alternative to standard methods for analysis of macro-nutrients in Mehlich 1 extracts of unfertilized forest soils
Fischer,
COMMUNICATIONS IN SOIL SCIENCE AND PLANT ANALYSIS. 2004. Vol. 35, Iss. 15-16; pg. 2191 - 2208
Here is the abstract for the article above:

Abstract

This study evaluates ion chromatography (IC) as an alternative to atomic absorption (AA) and inductively-coupled plasma spectrometry (ICP) for analysis of potassium (K), magnesium (Mg), and calcium (Ca), and as an alternative to antimonylmolybdate colorimetry and ICP for analysis of phosphorus (P) macro-nutrients in Mehlich 1 extracts. Soils typical of pine forests in the southeastern United States were tested. IC correlates well with AA and ICP for K and Ca, but not for Mg, unless conditions are chosen that resolve Mg from manganese (Mn). IC does not correlate very well with colorimetry for P at extract levels below 2 mg kg-1 or in extracts with high levels of dissolved organic matter complexes of aluminum (Al) and iron (Fe). ICP results for P exceed both IC and colorimetry by 3Ė5 mg kg-1 for all soils tested. The merits of IC relative to AA, ICP, and colorimetry for forest soil testing are discussed.

(this is why my wife calls it the alphabet science )

Kevin

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post #15 of 37 (permalink) Old 01-11-2005, 06:02 PM
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Quote:
Originally Posted by KevinC
Grad students - we don't have any here (unless you count MBA students and Biology Education MS students). The Citadel is undergraduate only in chemistry. If you want the experiments to take 10x longer with less reliable results, sure - we'll put some undergrads on it It is still nice to pay them or give them some course credit. Both of the papers I mentioned earlier had undergraduate student coauthors.
As a prior chemistry undergrad and current physical chemistry grad <laser microscopy>, I would encourage you to at least run rebuilding the IC by your chair. It is less of a novel technique so you might not get papers for rebuilding the LC alone but you may be able to conduct an interesting study to two.

Any chance of obtaining corporate funding? You might find some company willing to shell out some cash to boost their claims.

Moved to Tucson.
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