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Re: [APD] CO2 and Algae

Hi everyone.
Physiologically and chemically, there are some points.

In cases of submerged, vascular plant, their nutrient
source, especially phosphorus, is mainly from their roots.
Vascular plant absorb nitrogen from their leaves, too; but
phosphorus is the most important nutrient for vascular

In contrast, algae, such as phytoplankton, can absorb
nutrients only from water. Therefore, to preclude the
phytoplankton growth, it is effective to decrease nutrient
levels in water, especially phosphorus.

In cases of bubbling CO2 in water, one possible mechanism
to reduce phosphorus in water is the adsorption onto the
sediment. If higher free CO2 in water, pH value becomes
lower (neutral). This pH level can reduce phosphorus from
water by adsorbing onto the sediment particles. So, there
is little direct effect on phytoplankton by bubbling CO2.

In addition, higher free CO2 in water can increase
macrophytes growth because of the high carbon assimilation

--- Stuart Halliday <stuart at mytriops_com> wrote:

> I believe Bill wrote this email section below:
> > Standard advice to people whose aquariuims are
> plagued with algae is 
> > often, "Add more CO2."
> > 
> > That seems to work in many cases.  My question is,
> Why?
> > 
> > Does CO2 directly kill algae or stop it from
> multiplying?  I think not; 
> > as a plant, algae should benefit from CO2.
> Yes. I agree too.
> > Does CO2 enable plants to grow faster?  Yes.  But
> how does that affect 
> > algae?
> Algae is a plant also so they can grow faster too.
> But it is believed that (if no other nutrient is in
> short supply) then higher
> plants can absorb nitrogen quicker using the carbon
> to build internal
> structures and so there is less available for the
> algae to use.
> Maybe it's partly because algae is often seen in
> abundance on the glass walls
> which is at right angles to the overhead light and
> so has less
> photosynthesising power going on when CO2 is turned
> on?
> You'd need to ask Tom Barr at the Barr Report web
> site for a better answer!
> :-)
> -- 
> Stuart Halliday
> http://mytriops.com/
> 200 Million years in the making...
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