# An interesting paper on Eriocaulon



## _Maq_ (16 Jul 2022)

Shading by an invasive macrophyte has cascading effects on sediment chemistry

I happened to come upon an interesting paper which adds some interesting comments on topics recently discussed in this forum.

(1) Plants affect negatively algae growth in the way that they uptake nutrients from sediment, decrease the concentration gradient of nutrients between sediment and water column, less nutrients penetrate into the water column, and thus less nutrients are available to algae as a result. Besides, they oxygenate the rhizosphere, with the same result (phosphorus and transition metals remain insoluble, adsorbed to the sediment particles).
No allelopathy required.

(2) Eriocaulon aquaticum acquires nitrogen mostly as ammonium by roots and does not suffer from melting. (In fact, this is very common state of affairs in natural, non-eutrophic waters.)

(3) Eriocaulon uptakes CO2 by roots, and CO2 concentration in sediment is on the level comparable with that with CO2 injection (20 to 30 mg/L). We can ask then whether any CO2 injection is beneficiary for Eriocaulons at all.

(4) Most aquatic websites stubbornly insist that Eriocaulons require nutrient-rich substrate. Possibly because anyone can see that their roots are huge. Such assessment is almost certainly wrong. In the nature, Eriocaulons live in oligotrophic waters with nutrient-poor, sandy sediments, and create large roots to oxygenate rhizosphere and uptake CO2 generated by respiration of associated microbes.

(5) Similarly, carpet plants try to cover the sediment as densely as possible to uptake CO2 released from sediments before it gets diluted in the water column. Again, we can ask to what degree these plants benefit from CO2 injection.
(Well, the last point is actually not mentioned in the attached paper. I've read it somewhere else.)

What I don't understand is this: "Isoetid roots derive CO2 from the sediment porewater and release O2 into the porewater. These processes raise sediment redox potential, *which may decrease sediment pH*." Will anyone kindly enlighten me?


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## JoshP12 (16 Jul 2022)

With higher redox potential, the soil may be more likely to liberate H+ or exchange it?

That’s my immediate gut response - figured I’d share.

I’ll think a bit. 

Edit Sorry that’s not right — in the literal sense - but there will be a roundabout electron way to get there


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## _Maq_ (10 Sep 2022)

I have to admit, I'm largely unsuccessful in keeping _Eriocaulons_. Based on reading on their natural habitats, I keep them is acidic (pH 5 to 6) water, silica sand, and fertilize sparingly (0.2 mg/L phosphate, 2 mg/L nitrate equivalent - half ammonium, half nitrates).
What is your recipe for success with these plants? (Except CO2 injection, which is unacceptable for me.)


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## plantnoobdude (10 Sep 2022)

_Maq_ said:


> I have to admit, I'm largely unsuccessful in keeping _Eriocaulons_. Based on reading on their natural habitats, I keep them is acidic (pH 5 to 6) water, silica sand, and fertilize sparingly (0.2 mg/L phosphate, 2 mg/L nitrate equivalent - half ammonium, half nitrates).
> What is your recipe for success with these plants? (Except CO2 injection, which is unacceptable for me.)


What species have you tried?


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## _Maq_ (10 Sep 2022)

cinereum, Goiás, parkeri, Vietnam. 
Cinereum and parkeri bad, Vietnam ok, Goiás good so far but I keep it only a couple of weeks, and it's not growing any bit, yet.


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## plantnoobdude (10 Sep 2022)

_Maq_ said:


> cinereum, Goiás, parkeri, Vietnam.
> Cinereum and parkeri bad, Vietnam ok, Goiás good so far but I keep it only a couple of weeks, and it's not growing any bit, yet.


I would’ve suspected, the cinereum and vietnam to do well, hmm. 

It is my understanding that eriocaulon release oxygen and allow aerobic bacteria in sediment to release co2 for them? Not sure how this would be affected in plain silica sand vs an acidic substrate which they may prefer.


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## _Maq_ (10 Sep 2022)

Yes, many plants 'breed' microbes in their rhizosphere by releasing saccharides and oxygen and some of them - _Eriocaulon_ among them - then take up CO2 from microbial respiration. My sand is probably relatively poor in nutrients and detritus, but most _Eriocaulons_ come from oligotrophic waters, so this should not be the problem. I rather suspect that they are in trouble because of replanting from tissue culture. In other words, my poor substrate is not the problem, but they die off before they can fully establish their rhizosphere 'farm'. Just a guess, of course.


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## john arnold (1 Oct 2022)

in case anyone see this i recently did a tank with dwarf hair grass carpet and eriocaulon cenereum Co2 injection and it grew well, atlhough the roots were very shallow as i pulle dthem up if not carefull during maintenance but when i weend the tank off Co2 the eriocaulon stared to gade away, just an observation tomadd to the mix


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## hn5624 (18 Nov 2022)

Hello there,
I've grown all types of eriocaulon, including ones from seed on ebay. Probably all together 8-12 types so far.



_Maq_ said:


> (3) Eriocaulon uptakes CO2 by roots, and CO2 concentration in sediment is on the level comparable with that with CO2 injection (20 to 30 mg/L). We can ask then whether any CO2 injection is beneficiary for Eriocaulons at all.


I have noticed a couple things along with this as well.

1. I used a under gravel filter along with ada aquasoil + high co2 misting to grow mines with.
Perhaps the undergravel filter slowly pushes co2 from your water column (including the micro bubbles) into the root zone, kind of like a cool little hack for these guys.

2. I have noticed a temporary growth spurt from them lasting about a week after I use worm castings. I just dump worm castings directly on eriocaulon and within 1-2 days it falls within the cracks of the substrate into the root zone. Doesn't spike water parameters. Worm castings very very low in NPK, mostly just micro nutrients. I noticed that when I added worm castings there was a huge increase in microfauna (little underwater springtail population), to the point they would cover the walls. A theory is that worm castings break down in your substrate and massively increases co2 levels there temporarily as they break down.

3. Eriocaulons also seem to do very poorly if root space is confined. I've kept them in 2 inch open-cel hydroponic pots before with fresh ada aquasoil. The eriocaulons but extremely slowly, with roots coming out only from the bottom of the pot, onto the bare glass tank, almost as if searching for deeper substrate.

4. I am currently growing some Eriocaulon Ratnigiri again in charged kh/gh turface. (non-acidic very high CEC substrate mixed with worm castings) It's also got a light layer of akadama (long expired ph buffering capacity) just because I had some around.
I am using a very very big open celled pot. 10 inch wide and 10-12 inches deep.  It's open-celled as I believe as more access to water flow = better nutrient absorption and water column co2 access for the root zone.

I had used a 4 inch pot before with aquasoil and the eriocaulon essentially maxxed out the root zone in that pot (pot was transparent, roots were literally covering the walls of the pot) then started to grow leaves rapidly. I am  very curious to see how big eriocaulon Ratnigiri can get.

*On the internet people say its max 2 inches diameter. However... every single picture of this plant I see online uses only a 2-3inch deep substrate, I know for a fact its roots can go much deeper.  What exactly would happen if you gave it a 10 inch deep substrate? I would use ADA aquasoil instead of turface, but I am able to blast co2 and light much higher than normal with literally  0 algae as I am able to control nutrients better (both root and water column) with turface.*

These things love high light, does absolutely nothing but sit around in my tanks with medium light but high co2. I am currently giving it atleast 400+ par with a horticulture light. I would dare say 600+  par atleast according to the light par chart, but I can't confirm without using an actual par meter. I am getting the plant to pearl tho, so there's that.

*P.S, sorry for reviving a 2 month old thread.*


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