Intelligent Substitutions: CSM+B, Microplex, Fe DTPA - The Planted Tank Forum
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post #1 of 7 (permalink) Old 11-30-2013, 10:42 AM Thread Starter
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Intelligent Substitutions: CSM+B, Microplex, Fe DTPA

Or at least that's the best title I could think of. Perhaps "Musings of an Aquatic Madman" would be more descriptive. You know you've become obsessed when you watch the Macy's Thanksgiving Day Parade, see the big Santa balloon, and blurt out "Santa's got dropsy!" (I really did this.)


In the past I've been rather cavalier in my use of micros. Sometimes I've substituted Microplex for CSM+B on basis of iron content alone, ignoring all other differences. Many times I've probably added far more iron, or other micros, than is really necessary; assuming it to be harmless.

More recently my experiences have been that while deficiencies are to be avoided at all costs, it's also beneficial to limit excesses. My macro dosing has already undergone major changes to meet this philosophy, and I'm quite happy with the results. I figured it was time to give the micros the same treatment, even if the reward might be less, or even unnoticeable.

Micros are trickier, though. Most of us rely on a few commercial blends, sometimes with one or two key additions. Only the most hardcore planted tank enthusiasts go so far as to make their own micro blends entirely from individual ingredients for complete control. I'm not quite that hardcore! But I still had specific goals in mind, and I wanted to see if I could meet them without going to that extreme.

My Goals:

I'll preface this by saying that my goals may differ significantly from yours. That's fine. I invite you to keep reading if you desire to tweak your micros, as you may still find the example of how I achieved my goals useful to accomplishing a different set of goals.

1) I want a liquid micro solution, which is easier to dose into a wide variety of tank sizes. The solution should add 0.1ppm Fe per 5mL into a 10G high light/tech tank (you may consider this a light dosage, but keep in mind that I dose daily, as I find it easier to remember.)

2) I also want this solution to be usable in all my tanks, regardless of type. Dosage can simply be adjusted downwards for low light/tech tanks, but there is another issue to consider. In my low tech tanks, my tapwater's pH is high enough that the Fe EDTA in CSM+B quickly falls out of solution. In some cases, I've had to add triple the amount of CSM+B that would be EI dosed into a high light tank, to avoid visible iron deficiencies in a low light tank! Doing that, I worry a bit that all that iron - and other elements with lower toxic thresholds - are precipitating out and accumulating in the substrate. So instead I prefer to add extra Fe DTPA, which is more pH-stable.

3) But remember, I'm trying to both prevent deficiencies, and limit excesses. Iron in particular is under my scrutiny. I'm pretty satisfied with most aspects of CSM+B. But if I add more iron from Fe DTPA on top of CSM+B, then I get enough iron in low tech tanks, but a larger excess in high tech tanks. And if I reduce CSM+B to to prevent the latter, then I risk deficiency of other traces in all tank types. Well now, that's a conundrum, stuffed in an enigma, and wrapped in bacon. What I'd really like to do is take 50% of the Fe EDTA out of CSM+B and replace it with an equal amount of Fe DTPA, but that's impossible.

The Game Plan:

First off, I realized that CSM+B was a poor choice if I wanted to add Fe DTPA, yet limit iron. Microplex is lower in iron, so I suspected it might be a better trace mix to build on.

But it's also about 16X higher in copper. As I mentioned at the start, I have substituted Microplex for CSM+B on basis of iron content alone, meaning I dosed 16X more copper. Nothing bad happened, at least that I noticed. Of course, I don't keep shrimp, for which copper is more of a concern; yet even a few shrimp keepers have reported doing this substitution without issues. Let's assume for safety's sake that Microplex is near toxicity. Copper is reputed to have a narrow range between toxicity and deficiency. If that's true, then at 16X less CSM+B may actually be near deficiency! So a copper dosage somewhere between the two should be a good compromise. And so I add one more goal:

4) I want to limit tank copper levels to less than 0.15ppm, in an absolute worst-case scenario. With 0.15ppm being quoted a few places for treating algae and disease with copper, while still being relatively safe for plants and fish. And the worst-case scenario being that none of the copper dosed leaves the tank except by water change. Plant consumption is zero, or is equaled by copper contribution from fish food. In reality, copper levels will be lower, probably by quite a bit.

Achievement of Goals:

Time to crunch some numbers. But first a concise recap of all criteria:

I want to mix 1.875 cups (443mL) of a Microplex-based liquid micro solution, providing 0.1ppm Fe per 5mL into a 10G. It will be dosed daily, with a 50% weekly water change. At least 50% of the Fe must come from Fe DTPA. All other traces must roughly equal or moderately exceed the amount that would be provided by a reference solution providing the 100% of the Fe from CSM+B. Cu is an exception, it can exceed the reference by a large amount, but the worst-case Cu tank level of 0.15ppm must not be exceeded.

I'm using Yet Another Nutrient Calculator, created by [Wet]. It's a great tool, and does most of what I need.

First, I told it to compute the amount of Microplex I'd need in my solution to reach 50% of my target of 0.1ppm Fe per dose in a 10G (remembering the other 50% will come from Fe DTPA). The result was 4.192g. But that also provides 0.02ppm of Cu per dose. Does this exceed our theoretical worst-case limit? For 50% water changes and assuming zero net consumption, there's a super-easy way to calculate what maximum tank levels will trend towards. Take the number of doses between water changes. Multiply by ppm per dose. Then multiply by two:

7 * 0.02 * 2 = 0.28ppm

Oops, we're over by just about double. Well, I can fix that by just cutting Microplex dosage in half, and 0.14ppm comes in right under the limit.

This means that only 25% of my desired iron is coming from Microplex. I can further increase the Fe DTPA to fix that, but I want to make sure I haven't cut other micros too much in the process. So I also had the calculator determine the ppm's for a reference solution where 100% of my target of 0.1ppm Fe per dose comes from CSM+B. How does Microplex compare in such a situation?

(Note that for generating these numbers, I increased my targets by tenfold, then divided the results by ten, to reduce rounding errors in the calculator. Otherwise I get silly results like 0.03ppm Fe, even when I specified a 0.025ppm target.)

Surprisingly good, despite such a relatively small amount of Microplex:

* Molybdenum (Mo) is equal.
* Manganese (Mn) is just a wee bit lower.
* Zinc (Zn) is 50% higher, but as it's reputed to have a fairly high toxic threshold, I'm not going to concern myself with this for now.
* Magnesium (Mg) is also about 50% higher, but still an insignificant amount compared to what comes from tapwater or GH Booster.
* Iron (Fe) is correctable with Fe DTPA, and copper (Cu) is within my limit; both as intended.

But look at boron (B). Microplex falls down here, providing 6X less than the reference. I've heard that boron and iron are possibly antagonistic, meaning raising one reduces the available amount of the other; so a 5:1 ratio of iron:boron should be maintained. CSM+B approximately uses this ratio. I also found a post referencing an article from Tom Barr, claiming that his article endorses this ratio; though as the actual article is behind a paywall I have not read it.

Well, I can add one more thing to my solution, without feeling I've gotten too hardcore. Especially when that addition is readily available in grocery stores as either borax or boric acid! Since it will be a small amount, I'm choosing borax (~11% boron by weight) instead of boric acid (~18% boron by weight), which results in a larger and easier to measure quantity.

Unfortunately, Wet's calculator doesn't include either substance. Gotta do this the old fashioned way, with a little help from Google's unit conversion:

1) Our 443mL of solution is intended to be dosed at 5mL per 10G. The whole bottle is therefore a single dose for a (443/5)*10=886G tank.
2) The whole bottle will raise the boron of a 886G tank by only 0.003ppm. We want it to raise it by total iron (0.1ppm) divided by five, or 0.1/5=0.02ppm. The difference is 0.02-0.003=0.017ppm.
3) One ppm is 1mG/L. Our 886G tank is 3,354L. So we need to add (3354*0.017)=57mg of boron to the bottle.
4) Borax is only ~11% boron by weight, so we actually need 57/0.11=518mg of borax.
---If you're using a gram scale, stop here; otherwise, continue to convert to volume---
5) Borax density is 1.73g/cm3, so we need 0.527/1.73=0.3cm3 of borax by volume.
6) 0.03cm3 is 0.06 teaspoon. 1/16 teaspoon, at 0.0625, is close enough.

And finally, I am happy with my micro mix.

The Results:

Mostly just a warm fuzzy feeling that I'm doing the right thing for my plants. That I've finally given micros a little proper consideration. And a possibly interesting forum post for you.

I really expected no major real-world changes, and I was not disappointed. Going into week three of the new micro solution, things are still growing great as always. The plants don't seem to mind the reduced iron or increased copper.

There is one possible exception. My Limnophilia aromatica does seems to be growing fuller and faster. Right after noticing that, I saw an old forum post suggesting it likes extra zinc; and the new mix does provides 50% more. However, I'm not confident that the new mix is responsible. I'd have to do side-by-side controlled tests to convince myself of that, which I will probably never do.

Just One More Thing:

My new mix, by using Microplex, also addresses one small concern I've had with CSM+B. I'm stealing someone else's picture (but with credit) to show it, as their camera is far better than mine:

It's not very homogenous. Lots of distinct particles of different materials, with different particle sizes. I'm still on my original bag of CSM+B, nearly ten years old. At some point I noticed those different particle sizes started to separate out into differently colored layers. A good shake was required to mix it back up. But is that really enough to ensure consistent dosing?

Try looking for the copper. It's a good example to demonstrate my concern, since it's blue-green it's easy to visually isolate. You'll find relatively few particles of it. If you're dry dosing a tank with CSM+B, how many copper particles will you get in your small measuring spoon? One? Four? Zero? It will be different each time. Using a liquid solution helps, because since you're measuring out more CSM+B, variations will hopefully be averaged out. But it still wouldn't be completely consistent.

Now look at Microplex, picture from Green Leaf Aquariums:

At least visually, it's absolutely consistent. It will never separate or require shaking. Again, I get that warm fuzzy feeling using it; knowing I've eliminated another variable, even if it may be insignificant.

And with that I'm done. As I was filing the notes on this whole process away in my aquatic diary for future reference, I figured at least a few people might like to see them. So I wrote them up proper and posted. If you've made it this far, then you're probably one of the few, and I hope you find it useful.
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post #2 of 7 (permalink) Old 11-30-2013, 11:33 AM
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Great post! The lack of homogeneity in CSM+B coupled with the very small amounts I was using for dry-dosing my small tank convinced me I was getting random concentrations each time. That's the primary reason I made a micro solution - so I could use a much larger sample of the trace after shaking it up well and not worry about it. I also add Fe DTPA. And some Fe Gluc daily with my Excel dose. Overkill for my tank, surely, but I want to come up with a consistent process that'd work for future tanks.

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post #3 of 7 (permalink) Old 12-01-2013, 03:05 PM
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Interesting indeed. I use Miller myself, and you've identified a few of the areas I should be wary of, given that I dose extremely lightly. Thanks for sharing!
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post #4 of 7 (permalink) Old 12-02-2013, 04:06 AM
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Results from most trace mixes and ratios: never much more than warm fuzzy feelings, because, they are .....traces.

I've had low light crypt tanks handle a lot of traces.
I've dosed fairly light in high light tanks without much issue.

Plant species etc, many other more larger factors always take the front center stage compared to traces generally for most folks.

I've not seen any evidence in well over 20 years of a wide range of planted hobbyists using CMS+B of any negative effects even at very high lard it on dosing.

I add DTPA Fe and Fe Gluconate to CMS at a rate of about 4:1:1 by volume.
A very weak easy to use Fe, a moderate and then a stronger chelator for a wide mix and much higher amount of Fe, since it's the only one of real concern for aquatic plant growing, the soils/ADA As etc, those tend to have plenty and stay in solution much longer than Fe.

Does the chelator mix help? I suppose, particularly at harder KH's. You can simply dose more CMS alone...........and some more will be wasted, the chelator/ligand will just help improve the delivery % that the plant gets.

Given there's not much test to verify things, and the products are cheap and widely available, tossing all of the potential things into the "trace stew" that might help seems good.

Does it work? I guess.

In general, most hobbyists under dose traces, often grossly.
I've always made a liquid trace mix. Just from an old habit, but still always dose the other macro ferts dry.

FYI, copper toxicity is over rated, plants are very good at taking it up, Crypts can handle a lot(over 0.5ppm). As long as you prune and do not let the leaves rot etc, most will be okay. Some plants will do well, others, perhaps not, I'm not sure which as I've not bumped the copper up, rather, bumped the traces up overall.

SeaChem, Tropica master grow(or whatever they call it these days) and CMS+B and the various Fe chelators I've worked with.

As far as Fe uptake in aquatic submersed plants from ETDA chelated source,s there's only one study I know of that looked at uptake and optiomal growth and it was in Hydrilla.

Basiouny, Garrad and Haller 1977

They also did a test on Fe root and translocation using the same methods with 59Fe. I have the ability to do this in grad school, but I did not like the idea of using isotopes and they did not want to fund those items, they are PITA to track and the paper work makes it really not worth it unless you are certain of the question and the need.

Tom Barr
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post #5 of 7 (permalink) Old 12-02-2013, 02:19 PM Thread Starter
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Thanks to all who have posted their experiences and concerns!

Interesting to see two of the replies mention Fe Gluconate usage. I'll probably get some to add to my personal "stew", next time I can bundle it in on the shipping of something else I need.

To limit the length and scope of my original post, I did leave some personal motives out which better explain why I'm trying to reduce iron in particular. Which I'd like to add now.

Parameter issues often seem to multiply, rather than add. For example, combine a slight deficiency or huge excess on one nutrient, with a slight CO2 deficiency, and it can result in one large problem. Increase the CO2 a bit and it fixes the problem. Correct the nutrient issue instead, and it also fixes the problem.

Do both and not only does it fix the problem, but the tank is more robust and resistant to any other small issues that may unintentionally pop up later. This is a good thing.

And a doubly good thing if you're intentionally causing an issue. Currently I'm running all my CO2 injected tanks at 15ppm for various reasons and experiments. More recently even a high light tank, in which I want the reds typical of high light, without the too-frequent trimming. Nitrate limitation and medium light might provide similar reds and the reduced growth I want, but nitrate limitation isn't possible in this tank due to a high fish load. Short of using an adsorbent, a sump, or removing or underfeeding fish - all of which I don't really want to do - CO2 limitation seems to be the only solution. But I know I'll have to exercise tighter control over other parameters for this to have any chance of working. So far it's working well enough that, with a little additional tweaking, I think I can achieve my otherwise conflicting goals.

But even that still doesn't really explain why I'm reducing iron in particular.

Stef takes water from the main tanks and uses it as replacement water for her dozens of smaller betta tanks. All those tanks have at least some small plants, and fair lighting. The nutrients included in this "slightly used" water helps insure the plants can do their job of ammonia reduction, without having to do separate dosing. Plus water conditioners aren't necessary, and some beneficial infusoria regularly hitch a ride over as well. It's been working out very well. Conditions aren't optimal to prevent algae growth, but most algae is welcome since it too will improve water quality.

BGA is one obvious exception which appeared early, but Stef discovered a bit of dried banana leaf from our yard gradually eliminates it. That surprised me, so I tried a heavier proportion in a main tank with BGA on a filter outflow. The BGA was almost gone in a week. (I digress, as this isn't really related to iron - just interesting enough to mention regardless.)

Then it was green hair, which is actually attractive, and therefore welcome. However, in recent months the dominant algae has changed to some slimy reddish-brown fuzz. I'm not sure exactly what it is, but the color is highly suggestive that it's ferrophilic (iron loving). It's ugly. Stef doesn't like it. She wants the hair algae back. And the appearance of this new algae roughly corresponded to a time when I was using more iron in the main tanks, which really wasn't doing anything beneficial that I could tell.

So that at last is why I'm reducing iron. To hopefully, without causing an issue in the main tanks, solve an issue in an entirely different set of tanks. As convoluted as this may seem, it seems to be working - the main tanks are unaffected, while there seems to be a slow reduction in the amount of this undesirable algae in Stef's betta tanks.

And this whole thing makes me wonder. We're all familiar with the concept of "reading" the plants and algae, to let us know what needs to be changed. Stef's betta tanks are obviously further from optimal conditions for algae prevention than the main tanks. Might they be functioning as an "early warning system" of sorts? Are they exaggerating some nutrient issues that exist in the main tanks, but below the threshold of visibly manifesting there? And by taking some cues from them, can I keep the main tanks closer to optimal; heading off problems before they can actually appear? May be far-fetched, but it sure is an interesting idea.

As I've certainly broadened the scope of discussion, you are invited to do the same. Let's talk trace! Factual, speculative, anecdotal; it's all welcome.
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post #6 of 7 (permalink) Old 12-02-2013, 04:14 PM
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Food from the other tanks might play a role, there is Fe trace in the food.
Riparium/emergent growth, driftwood tannins, non CO2, these play roles and might offer better, simpler, more consistent results.
Lowering the KH also.

Quite a few options there.

Fe limitation can work, same as PO4 limitation, why not use that instead to slow plant growth as plants are well adapted to PO4 limitation and you get better coloration?

Certainly easier. See old APD post on the Fe PO4 limitation, should still be a fair amount there.

Why are you adding CO2? Plenty of non CO2 enriched tanks do quite well. The only good reasons I know of to add CO2 are to prevent CO2 competition between species and to increase rates of growth. CO2 consumption/competition is reduced if you limit a fert.

But then you lose a lot of the enhancement you gained from adding CO2, you cut off your foot to spite your toe. Since competition/consumption of CO2 is reduced, seems going a non CO2 route might offer the better option.
Certainly simpler too. If you do not like that much growth, water changes, dosing........whatever...........then do not add it. Or just use Excel etc.

I'm able to do that with non CO2 tanks quite well. About the easiest management for aquarium there is. Excellent for breeding. I've almost never had any algae issues, less than a CO2 enriched tank certainly.

The tannin and lower KH's might be useful for the Fe issue. That might play a role if what you see with the algae. See if adding peat etc helps. I bet it will.

Tom Barr
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post #7 of 7 (permalink) Old 12-02-2013, 05:40 PM Thread Starter
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Originally Posted by plantbrain View Post
Fe limitation can work, same as PO4 limitation, why not use that instead to slow plant growth as plants are well adapted to PO4 limitation and you get better coloration?
I've tried PO4 limitation in the past, in the tank in question. There was a wide variation in plant response. It's been a few years but I do recall that Ludwigia repens in particular pretty much stopped growing altogether, by the time most other plants were just starting to slow down.

And it's not something I could do again anyway. Like I mentioned with nitrates, given the current fish load in that tank, any useful amount of phosphate limitation is impossible without resorting to seafood dinners or other unacceptable measures.

Originally Posted by plantbrain View Post
Why are you adding CO2? Plenty of non CO2 enriched tanks do quite well. The only good reasons I know of to add CO2 are to prevent CO2 competition between species and to increase rates of growth. CO2 consumption/competition is reduced if you limit a fert.
Essentially the same reason, individual plant response. Some plants are never really healthy unless a bit of extra CO2 is present. A mere few ppm above atmospheric equilibrium. More than that isn't necessary for health, it just controls growth rate, until you reach another limiting factor.

Excel helps these plants, but it doesn't seem to work quite as well as bit of real CO2.

And if these plants are growing really healthy in a non-CO2 enriched tank, I betcha it's a tank with an organic substrate. But that's not really a non-CO2 enriched tank. Doesn't matter to the plants whether the CO2 comes from decomposing organics or a bottle.

I don't use organic substrates, so CO2 injection it is.

I'm curious if you've tried running CO2 injected tanks, but at ppms from 5-15, rather than the typical 30ppm or not at all. Especially at medium light, it's proving to be quite advantageous. You can put a small DIY bottle on a large tank, run it for three weeks, easy and cheap. CO2 stability seems to be much less of an issue than at higher ppms as well, so no algae and no need for pressurized. I've been doing that for a while now, and have yet to find a downside. It's only recently I'm experimenting with 15ppm and high light.

Originally Posted by plantbrain View Post
The tannin and lower KH's might be useful for the Fe issue. That might play a role if what you see with the algae. See if adding peat etc helps. I bet it will.
I won't bet against you there! But I have yet to try peat. Neither I or Stef are a fan of tannin-stained water. Stef in particular wants to be able to see her bettas' true colors clearly as they develop. Staining from indian almond leaves was part of what prompted her to experiment with banana leaves instead.

Many ways to accomplish a goal, just a matter of finding a way that appeals to you personally.
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