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Do Plants Need CO2?

Contents:

  1. No CO2 plants
    by "Roger S. Miller" <rgrmill/rt66.com> (Fri, 25 Sep 1998)
  2. No CO2 plants
    by krandall/world.std.com (Mon, 21 Sep 1998)
  3. No CO2 Plants
    by "Alysoun McLaughlin" <alysoun.mclaughlin/ncsl.org> (Fri, 25 Sep 1998)
  4. Necessity of CO2
    by "Roger S. Miller" <rgrmill/rt66.com> (Thu, 24 Sep 1998)

No CO2 plants

by "Roger S. Miller" <rgrmill/rt66.com>
Date: Fri, 25 Sep 1998
To: APD

On Fri, 25 Sep 1998, Kelly Beard asked:
>
> What plants grow well without the addition of CO2?

It would probably be easier to list the plants that require added CO2.

> Most of my plant
> experience is with Barclaya Longfolia, Amazon Swords and Anubias Bartari
> (?sp).  I'm guess most Anubias won't care, and I seem to remember from here
> and web pages that Crypts don't really seem to care either.

Many of the common aquarium plants grow fairly well (usually slowly)
without CO2, as long as other condition are conducive to growth.  The
light level makes a difference, as does the combination of plants in a
tank.

An example... I've grown A. barteri nana in tanks without added CO2 for
some time.  It grows very well under moderate to low light in combination
with other plants that grow well under low light.  It also grows in
sunlight as long as the competition for the limited CO2 supply isn't too
intense.  Small fish and shrimp like to hide in the protection of their
roots, and I think their CO2 output helps the plant compete.  When I add
Val.  (a very competitive plant) to that setup the anubia stopped growing
and eventually died.  Java fern and a myriophyllum both failed under those
same conditions.

I'm not sure I have enough experience with this to generalize, but it
looks to me like amphibious plants or plants that naturally grow partly or
entirely emersed don't compete well for low CO2 supplies under bright
light.  The same plants can grow very well without added CO2 as long as
the light is moderated.

Conversely, plants that naturally grow fully submersed are likely to
compete and grow well without added CO2.  There is at least one exception
to this, as Cabomba caroliniana doesn't seem to do well without added CO2
- - an observation I find a little difficult to explain.


Roger Miller


No CO2 plants

by krandall/world.std.com
Date: Mon, 21 Sep 1998

Kelly Beard wrote:

>What plants grow well without the addition of CO2?  Most of my plant
>experience is with Barclaya Longfolia, Amazon Swords and Anubias Bartari
>(?sp).  I'm guess most Anubias won't care, and I seem to remember from here
>and web pages that Crypts don't really seem to care either.

What plants will grow well without supplemental CO2 depends greatly on your
water conditions, substrate and light level.  It's not quite true that
Anubias and Crypts "won't care".  Both can be grown very successfully in
tanks without supplemental CO2 _providing_ that the light level is in
equilibrium with the amount of CO2 available.  At higher light levels,
they'll definitely benefit from some supplemental CO2.  

Plants are 43% carbon by dry weight, and they need to meet the need fro
carbon in some way.  Some can do it by using carbonates directly from the
water. Although this can be detrimental in the aquarium if you don't watch
your KH closely.  Vals and Ceratophyllum fit this category.  They will grow
well in a non-supplemented tank with a high KH, but will quickly fail in a
tank with very soft water.

Some people, including myself, feel that Crypts are better than some plants
at meeting their CO2 requirements via the substrate, and that makes them
good candidates for non-CO2 supplemented tanks _as long as_ the substrate
is adequate.

Other plants can meet their carbon needs in a non-supplemented tank by
developing floating and/or emergent foliage.  Water sprite, Azolla and many
other fit this category.

Many Anubias seem to be able to adjust their growth to whatever is
available to them.  Rather then failing if the nutrient mix isn't right, or
id light is inadequate, they simple slow down and hold on anyway.

So I guess the short answer is, "It depends."<g>


Karen Randall
Aquatic Gardeners Association


No CO2 Plants

by "Alysoun McLaughlin" <alysoun.mclaughlin/ncsl.org>
Date: Fri, 25 Sep 1998

>Date: Thu, 24 Sep 1998 15:02:31 -0500
>From: "Beard, Kelly" <KBeard-at-comdata.com>
>Subject: No CO2 plants
>
>What plants grow well without the addition of CO2?  Most of my plant
>experience is with Barclaya Longfolia, Amazon Swords and Anubias Bartari
>(?sp).  I'm guess most Anubias won't care, and I seem to remember from here
>and web pages that Crypts don't really seem to care either.


I've never yet actually added CO2, and I've never had the kind of growth
that would allow me to propagate and sell my plants, but I've had a wide
variety of plants 'grow well', meaning hold their own next to the plants in
the hobbyist books, and currently have these plants in my tank:  various
hygro sp., rotala, ambulia, water sprite and wisteria, various amazon
swords, dwarf grasses, crypt wendtii.

Alysoun McLaughlin


Necessity of CO2

by "Roger S. Miller" <rgrmill/rt66.com>
Date: Thu, 24 Sep 1998

Ms. McLaughlin brought this up, so I'll comment.

It isn't necessary to add CO2 to have a lush and beautiful planted tank,

BUT...

Your light levels and your CO2 levels need to be balanced for the type of
plants that you want to grow.  I think that if you want to grow a wide
variety of plants in one tank under high light conditions then you will
need to add CO2.  If you stick to plants that are well adapted to
submersed growth and capable of competing for low CO2 levels and/or using
bicarbonate as their carbon source then you can use high light without
CO2.  Under lower light conditions even plants that aren't real
competitive at low CO2 levels can grow beautifully, although more slowly.

Some plant keepers also use CO2 levels that are higher than the minimum
they need so they can promote rapid growth. The rapid growth provides a
nice advantage; plants that are growing rapidly can quickly replace
damaged leaves, fast-growing stem plants can be pruned and replanted
and older damaged or algae-ridden stems can be removed or hidden.  This
gives them more flexibility in their aquascaping and makes it easier to
maintain an attractive tank.

When you use extra CO2 to promote rapid growth you also have to make sure
your fertilizing regimen keeps apace with plant growth, or growth will
slow down and deficiency symptoms will damage the vigor and beauty of the
plants.  The amount of hands-on maintenance also increases as the growth
rate increases and the possibility of uncontrolled nuisance algae growth
increases.

So while CO2 isn't necessary, using CO2 gives us a way to fit our tanks to
our needs.  It's up to the aquarist whether they want the extra
flexibility, high growth and high maintenance promoted by adding CO2, or
whether they want the lower growth and correspondingly lower maintenance
that comes with little or no CO2.


Roger Miller

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This page was last updated 29 October 1998