[Wet Thumb Forum]-Lets talk about iron and micros. Experts only. - Fertilizing

m.lemay · 01-08-2005, 02:16 PM

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

m.lemay · 01-08-2005, 02:16 PM

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

TWood · 01-09-2005, 02:22 PM

I'm no expert (few here are) but...

<BLOCKQUOTE class="ip-ubbcode-quote">quote:<HR>It can take weeks for plants to respond to micros. <HR></BLOCKQUOTE>

I use the color of new growth on h. difformis as an indicator for low iron (Fe) - Pale growth means Fe is too low. The plants respond within HOURS after adding CSM+B to get Fe at 0.1ppm.

<BLOCKQUOTE class="ip-ubbcode-quote">quote:<HR>Do we need more iron than Plantex CSM+B offers? <HR></BLOCKQUOTE>

That question makes no sense and reveals an underlying confusion. CSM+B has a known amount of Fe in it. If you want more Fe in the tank, then add more CSM+B to the tank. Use the Fertilator to dose as much as you want to get to a target level:

http://www.aquaticplantcentral.com/forum/fertilator.php

Don't bother making a solution, just add the dry powder until the calculator says you've added enough. I usually dose to get 0.1 ppm Fe.

Remember too, the dosing for Fe, when part of a micromix, is also used as a proxy to get the other micronutrients correctly dosed. The idea is, that if you dose Fe to a certain level, then all the other micros will fall into line in the proportion that they exist in the micronutrient mix. Just dosing Fe alone doesn't accomplish that broader goal.

TW

m.lemay · 01-09-2005, 03:24 PM

You're assuming that Plantex is the perfect mix for all plants all the time.

The question makes a lot of sence in that ,what if as your dosing plantex your overdosing unnecesary and potentially dangerous elements such as copper (present in Plantex)in order to obtain the optimum iron level. All the other stuff you stated is all true but far too simple for this discussion.

Roger Miller · 01-09-2005, 03:57 PM

Most if not all of the mico nutrients have been determined to be harmful to aquatic life at rather low levels. That does not mean that any of them would be toxic to whatever you keep in your aquarium. Nor does it mean that you would necessarily observe the damage even if it were present. Some levels according to the EPA goldbook are:

Iron 1 milligram/liter dissolved, any form.
Boron 750 micrograms/liter
Nickle 119 micrograms/liter at 4 dGH (long term)
Zinc 80 micrograms/liter at 4 dGH (long term)
Copper 9 micrograms/liter at 4 dGH (long term)

The "safe" level of nickle, zinc and copper increases with hardness; also levels for short term exposures are higher than levels for long term exposures. The standard for iron is for any dissolved form including chelated and complexed forms. The standard for boron is actually established for irrigation water and may consider effects from evaporative concentration in soils.

Using tested iron levels as an indicator for other trace nutrients is an established practice. The chemistry of iron is different from the chemistry of other trace nutrients. As a result, iron is a very poor indicator of trace nutrient levels.

Marcel, I hope you don't expect very many responses on this thread.

Roger Miller

TWood · 01-09-2005, 04:30 PM

<BLOCKQUOTE class="ip-ubbcode-quote">quote:<HR>Using tested iron levels as an indicator for other trace nutrients is an established practice. The chemistry of iron is different from the chemistry of other trace nutrients. As a result, iron is a very poor indicator of trace nutrient levels. <HR></BLOCKQUOTE>

Hey Roger,

But what about not testing for iron, but simply dosing a micromix to a mathematically derived iron level? Don't the micros then fall into line behind the iron at the ratios they are present in the mix? Which does raise the question, which ratio is correct? I suspect different agricultural micromixes are designed to address regional soil conditions.

Edit: Snarky comment removed.

TW

Roger Miller · 01-09-2005, 05:47 PM

<BLOCKQUOTE class="ip-ubbcode-quote">quote:<HR>Originally posted by TWood:
But what about not testing for iron, but simply dosing a micromix to a mathematically derived iron level? Don't the micros then fall into line behind the iron at the ratios they are present in the mix? <HR></BLOCKQUOTE>I can't think of a reason in the world why they should. That's why iron is a lousy indicator.

Iron hangs around in the water as long as it stays chelated then drops out of solution very quickly when the chelate breaks down. That breakdown rate depends on the kind of chelate, the pH, light spectrum and intensity, temperature and probaby a few other things. Very little of the iron actually gets used by plants. None of the other trace elements react the same way. Some of the trace elements have little tendency to react or precipitate and may stay in the water until plants use them. Copper, zinc, and nickle do not precipitate but might adsorb to surfaces -- whatever they do they certainly wouldn't do it at the same rate as chelated iron. Manganese tends to react a little bit like iron, but not under the same conditions and probably not at the same rates.

If you use iron as your standard (regardless of whether you test it or calculate it) then nutrients that are more conservative (less reactive) than chelated iron tend to build up in the water. Nutrients that are less conservative (more reactive) than chelated iron will tend to be depleted. You could get some real different behaviors out of two different trace mixes that are identical in every regard except the chelating agent used for the iron.

For the record, I use a commercial trace mix without iron and a commercial iron solution and I don't test or calculate a damned thing. Doses are determined from the manufacturer's recommendations and adjusted based on plant growth and on the principle that the dose of potentially toxic additives should be minimized.

I can dose iron rather freely because its toxicity is fairly low. In the case of other traces:

I dose a trace nutrient mix at the lowest rate necessary to avoids deficiency problems in most plants.

I try to avoid dosing things that the plants don't need. My tap water contains plenty of boron so I use a trace mix without boron.

I use substrate amendments to treat cases where one plant shows a deficiency that isn't shown by other plants in the same tank. That lets me avoid using higher doses.

I use small daily doses to avoid the high concentrations that result from a large dose delivered at longer intervals.

The possible behaviors of trace elements in the aquarium can vary greatly based on conditions in the aquarium. The need for dosing can be even more variable than the behavior of the chemicals. It's (to me) laughable to think that the trace nutrient needs of all aquariums can be satisfied just by using a trace mix and dosing to a predetermined iron level.

Roger Miller

TWood · 01-10-2005, 03:04 AM

<BLOCKQUOTE class="ip-ubbcode-quote">quote:<HR>It's (to me) laughable to think that the trace nutrient needs of all aquariums can be satisfied just by using a trace mix and dosing to a predetermined iron level. <HR></BLOCKQUOTE>

Huh, well my apologies then to Marcel. More complexity is involved.

Except, doing just that DOES work (for me) so I'm not convinced that the additional layers of complexity are helpful.

TW - Bowing out to the experts...

m.lemay · 01-10-2005, 03:12 AM

Roger: Thanks very much for the replys. I have a similar thread going over at theplantedtank site. Some of the things you've mentioned are enlightening. Unfortunately I don't have time to reply right now but I will in the next few days.

TWood · 01-10-2005, 05:48 AM

As a follow-on, here's a comparison of products:

http://www.gpodio.com/fert_table.asp

An excerpt below. What's not clear to me is whether or not they are using the same method to calculate percentages. By weight, volume, or molecular weight? The ratios are way different, and may be explained by differences in the accounting method.

TW