Live Aquarium Plants

"Altum" wrote in message
. com...
Mister Gardener wrote:
On Tue, 09 May 2006 21:23:33 GMT, Altum
wrote:


lot of plants. Normally, you use an airstone/surface agitation to get
atmospheric CO2 into the tank.

Huh? You lost me.

-- Mister Gardener
-- Pull the WEED to email me

Surface agitation keeps air and water CO2 in equilibrium just as it does
with oxygen and other gasses. If you are NOT adding extra CO2, plants
deplete the CO2 in the tank much as fish deplete oxygen. Surface
agitation helps add CO2 back into the water.

Adding CO2 gas to a fishtank artificially raises CO2 levels above the
normal equlilbrium levels. At this point, you want to reduce surface
agitation because the extra CO2 you carefully added will be driven back
out of the water.


I wonder is you're using the old slide rule, or the new-fangled Texas
Instruments or HP...Your conclusion made haunting good sense. I'm still
swirling it around ......

On Wed, 10 May 2006 00:38:16 GMT, "-ED" wrote:


"Altum" wrote in message
.com...
Mister Gardener wrote:
On Tue, 09 May 2006 21:23:33 GMT, Altum
wrote:


lot of plants. Normally, you use an airstone/surface agitation to get
atmospheric CO2 into the tank.

Huh? You lost me.

-- Mister Gardener
-- Pull the WEED to email me

Surface agitation keeps air and water CO2 in equilibrium just as it does
with oxygen and other gasses. If you are NOT adding extra CO2, plants
deplete the CO2 in the tank much as fish deplete oxygen. Surface
agitation helps add CO2 back into the water.

Adding CO2 gas to a fishtank artificially raises CO2 levels above the
normal equlilbrium levels. At this point, you want to reduce surface
agitation because the extra CO2 you carefully added will be driven back
out of the water.


I wonder is you're using the old slide rule, or the new-fangled Texas
Instruments or HP...Your conclusion made haunting good sense. I'm still
swirling it around ......

Yeah, well, when you're done swirling it around, spit it out and
explain it to me. Meanwhile, I'm shutting down this generic machine
and going to watch another sweet victory for Boston.

-- Mister Gardener
-- Pull the WEED to email me

Mister Gardener wrote:
On Wed, 10 May 2006 00:38:16 GMT, "-ED" wrote:


"Altum" wrote in message
.com...
Mister Gardener wrote:
On Tue, 09 May 2006 21:23:33 GMT, Altum
wrote:


lot of plants. Normally, you use an airstone/surface agitation to get
atmospheric CO2 into the tank.

Huh? You lost me.

-- Mister Gardener
-- Pull the WEED to email me

Surface agitation keeps air and water CO2 in equilibrium just as it does
with oxygen and other gasses. If you are NOT adding extra CO2, plants
deplete the CO2 in the tank much as fish deplete oxygen. Surface
agitation helps add CO2 back into the water.

Adding CO2 gas to a fishtank artificially raises CO2 levels above the
normal equlilbrium levels. At this point, you want to reduce surface
agitation because the extra CO2 you carefully added will be driven back
out of the water.


I wonder is you're using the old slide rule, or the new-fangled Texas
Instruments or HP...Your conclusion made haunting good sense. I'm still
swirling it around ......

Yeah, well, when you're done swirling it around, spit it out and
explain it to me.

Altum's point is quite valid although their are a few 'ifs and buts"
you need to consider. Nature likes equalibrium. If left to it's own
devices ie no surface agitation CO2 in the air and water should reach
equalibrium ie the amount of CO2 released from the water will equal the
amount entering into solution. Agitation circulates water at the
surface dispersing the high CO2 concentration at the surface with the
CO2 concentration at lower water levels and allowing more CO2 to
dissolve. As a result it will reach equilibrium faster.

In a CO2 supplemented tank the concentration of CO2 in the water is
higher compared to the air and it's desireable to maintain this
inequalibrium. In a CO2 supplemented tank, the CO2 concentrations the
surface is lower than the rest of the tank (because the air at the
surface has lower CO2 than the lower levels of the water). Co2
supplementation dissolves CO2 faster than the surface releases it. If
you provide surface agitation, the water now increases the rate of CO2
loss in an effort to reach equalibrium with the air. Botom line you
waste a lot of the CO2 you're trying to put in.

Now for the ifs and buts with aerating a planted tank without CO2
supplementation. When you throw a plant into the equation it will use
the CO2 in the water and put the system out of equilibrium. If the
plants requirements exceed the rate at which CO2 can be absorbed by the
water CO2 will be depleted in the tank. As agitation increases the rate
at which the CO2 concentration reaches equilibrium, agitating the water
will the replenish the CO2 faster, preferably at a rate faster than the
plant will use it. Of course, if we also have fish in the system to
supply CO2 you need to factor in the amount of CO2 given of by the fish
and the amount used by the plant when determining whether it's
desireable for the tank water to be at equalibrium or whether you're
cheating yourself of CO2. In a well planted tank CO2 from the fish is
probably not an issue. In a well stocked tank with a few plants it may
or may not be. A simple experiment to determine this would be to
measure CO2 in the tank without aeration and compare it to a bucket of
tank water after a few hours aeration and see if there is any
appreciable difference... if you can be bothered. If you're not adding
CO2 chances are there is not enough difference between aeration and no
aeration to make a difference.