Emersed?

[waterdrop]

I'm interested in hearing some discussion of what people happen to know about the whole topic of how some plants grow better "emersed" as opposed to "submerged."

Here are some random things I've heard regarding this but I'm not experienced enough to put them in context:
1) Most aquarium plants grow emersed in their natural habitat, not submerged. (True?False? ??)
2) (related) True submerged-only plants are rare in freshwater natural habitats.

What about partial emersion vs. time emersion? I've seen some slide shows of plant collection trips where collectors where I've heard comments that some of our aquarium plants live completely out of water some of the time, whereas at other times the are partially submerged and at other times fully submerged.

I've heard that plant leaves can get much more CO2 when out in the air, but what about partial emersion, do plants that stick out above the water surface get an extra kick of CO2 from this? Is this part of what our extra sourcing of available CO2 is all about? Is a significant part of the CO2 effort all about trying to help emersion plants be ok as submersion plants, or is it more a continuum of just better provision of the carbon nutrient and there's a complete mix of what the plants might be used to from an evolutionary standpoint?

Please, I know this topic may look sort of stupid or boring but I'd enjoy hearing your thoughts!

 

[Truck]

1) Most aquarium plants grow emersed in their natural habitat, not submerged. (True?False? ??) yes and no, yes in the wet season and no in the dry season
2) (related) True submerged-only plants are rare in freshwater natural habitats. not sure on that one

 

[aaronnorth]

1) Most aquarium plants grow emersed in their natural habitat, not submerged. (True?False? ??)

like truck says, but it depends on what you call aquarium plants, most of the plants we use are marsh plants whereas some are 100% aquatic like vallisneria sp

2) (related) True submerged-only plants are rare in freshwater natural habitats.

not sure, i know that most plants that we buy are grown from plant tissue and cuttings so we do not affect natural stock much.

What about partial emersion vs. time emersion? I've seen some slide shows of plant collection trips where collectors where I've heard comments that some of our aquarium plants live completely out of water some of the time, whereas at other times the are partially submerged and at other times fully submerged.

Again suppliers grow their plants emerged as they can keep a closer control over the plants, plus running costs are lower - particularly CO2 costs (as its free!)

I've heard that plant leaves can get much more CO2 when out in the air, but what about partial emersion, do plants that stick out above the water surface get an extra kick of CO2 from this?

Yes,
if you wan to see some videos of how plants are grown by aquafleur then see here: http/www.superfish.nl/site_en/aquafleur.php

 

[Dave Spencer]

2) (related) True submerged-only plants are rare in freshwater natural habitats.

Vallisneria sp is one of very few true aquatic species.

I've heard that plant leaves can get much more CO2 when out in the air, but what about partial emersion, do plants that stick out above the water surface get an extra kick of CO2 from this? Is this part of what our extra sourcing of available CO2 is all about? Is a significant part of the CO2 effort all about trying to help emersion plants be ok as submersion plants, or is it more a continuum of just better provision of the carbon nutrient and there's a complete mix of what the plants might be used to from an evolutionary standpoint?

Plants preferred choice of carbon is gaseous, which is why using ceramic diffusers is the best method. Bubbles of gaseous CO2 are caught beneath the leafs. I got more pearling when I used to use ceramic diffusers. Aqueous carbon via CO2 dissolved in the water is the next best preferred source, followed by organic carbon.

I have mosses and Bolbitis heudolotii growing out of the water, and there is a noticeable difference in the emersed and submersed part of the plants.

30ppm CO2 is the target in a high light planted tank so that it is a non limiting nutrient, but still at a level that is comfortable for the fauna.

Dave.

 

[waterdrop]

1) So are we doomed to failure trying to keep all these emergent plants (other than Val) always submerged? Well, clearly we're not.. witness all the great looking planted tanks, but are we making up for it with our providing of the CO2?

2) AAhhh, seasons!... yet another way that our keeping of plants is unnatural, besides emersion! Anybody ever try to mimic any aspects of seasons in their planted tank??

3) Let me make sure I understand this distinction between gaseous CO2, dissolved CO2 and organic carbon.

a) When you say gaseous, am I right in assuming we're talking either about the open atmosphere (leave above water surfact) or visible bubbles of CO2 (bubbles of CO2 make it into the tank to come into direct contact with plant body?)

b) OK, and by dissolved do we mean to say that some small percentage (much lower percentage than air, right?) of CO2 molecules are no longer in bubbles but are isolated and surrounded by water molecules, right?

c) And why is a ceramic diffuser the best method? Is it that this puts the little microbubbles floating out into the tank and then into direct contact with the leaves -without- being dissolved? I can't quite understand the mechanism for why the plant would care if the CO2 is in a bubble versus being a single molecule floating up next to the plant in the water.

d) And further, are you saying that a reactor that churns the bubbles into the filter inlet pipe is going to be worse because more of the CO2 gets dissolved?

 

[waterdrop]

Which could absorb more CO2? A wet leaf out in the air or a dry leaf out in the air?

 

[Dave Spencer]

Which could absorb more CO2? A wet leaf out in the air or a dry leaf out in the air?

Stop thinking too much!

Plants with access to atmospheric CO2 will have a limitless supply, so I don`t see why a wet leaf should find it harder to acquire C. It is possible to increase growth rates of terrestrial plants by growing them in an environment of increased CO2 levels, but I don`t see a wet leaf impeding C uptake, but I could be wrong.

The as to why microbubbles in the tank are the best method of delivering CO2 is unknown, as photosynthesis is largely maxed out at 30ppm CO2 in aquatic plants, so the gaseous CO2 may not be supplemental to the 30ppm of aqueous CO2. I have used several methods of CO2 diffusion, but have always found ceramic diffusers to bring the best growth and pearling. A lot of people have made this observation, and it is easily tested. Aesthetics dictate that I no longer use ceramic diffusers.

Dave.

 

[Miss Wiggle]

Which could absorb more CO2? A wet leaf out in the air or a dry leaf out in the air?

Stop thinking too much!

took the words right out of my mouth! WD you don't half ask some complicated questions.....

 

[waterdrop]

"Stop thinking too much! "

Ha Ha ... You guys know my story by now. I've set up my son's little tank and am trying to "re-learn" the hobby after a gap since the 60s/70s and for now the family more or less limits how much I can get into the hobby (holds me back from much action.) I'm fascinated enough that I even drove down the the International AGA conference in Atlanta this last time... which multiplied my questions by thousands, but helped me understand more stuff too (I'm dying to talk to somebody about some of those "bigger picture" questions as I felt that I saw for the first time how alive the different approaches to planted tanks still are and that the fact that people do have success with some pretty dramatically different techniques makes things complicated!) BUT, its a totally different thing to actually do it in your tank than to talk about it of course and feeble attempts in my son's tank so far are laughable compared to the stuff you guys do. I am so efficient at killing plants that my tank never even looks as good as half the grade-school beginners who post in the beginners section! I can't do it yet, but when I start taking more significant steps I know you guys will help me diagnose my problems. Its just for now I'm pretty much limited to asking questions and trying build up a foundation of plant learning

~~waterdrop~~

 

[aaronnorth]

am so efficient at killing plants that my tank never even looks as good as half the grade-school beginners who post in the beginners section!

probably because you trying to get everything "too perfect"
get an arcadia acr tank with 11w lapm and place some anubias, microsorum and some java moss in with a weekly fert and they will do fine

1) So are we doomed to failure trying to keep all these emergent plants (other than Val) always submerged? Well, clearly we're not.. witness all the great looking planted tanks, but are we making up for it with our providing of the CO2?

yes... and suffixient nutrients

2) AAhhh, seasons!... yet another way that our keeping of plants is unnatural, besides emersion! Anybody ever try to mimic any aspects of seasons in their planted tank??

no because it is not necassary and if we can have plants growing fine then why would e want to do it?


gaseous = gas - so in the air or bubbles
Aqueous = water - so CO2 dissolved in water (you cant see it)

 

[waterdrop]

The as to why microbubbles in the tank are the best method of delivering CO2 is unknown, as photosynthesis is largely maxed out at 30ppm CO2 in aquatic plants, so the gaseous CO2 may not be supplemental to the 30ppm of aqueous CO2. I have used several methods of CO2 diffusion, but have always found ceramic diffusers to bring the best growth and pearling. A lot of people have made this observation, and it is easily tested. Aesthetics dictate that I no longer use ceramic diffusers.

OK, so this sounds really interesting, an observation by the hobbyists but no good explanation! I assume its a fairly subtle difference?

Am I right in thinking that a reactor in the filter intake tube would basically result in the aqueous CO2 without any of the little microbubbles making it through and ever looking like what a ceramic diffuser would put out?

Did you just decide the little glass device with the little white wafer in it was too distracting to the aquascape?