Plants in the Wild and CO2 Sources?

[DGalt]

In reading about planted aquariums and whatnot, and the issue of needing to artificially introduce CO2 into an aquarium, I came to wonder where exactly plants in the wild get their CO2.

I understand why we need to introduce fertilizers into the tank. The soil that plants thrive in contains nutrients that have only come to exist in said soil from centuries of organic decay (we have a poster in the plant science lab that shows a time line showing the major events that occurred in the amount of time it took 1 inch of soil to be "created" - it spans something like 600+ years).

But why do we need to add CO2? Our need to add CO2 means there must be some source in the natural environment that we cannot provide in an artificial environment. It can't be the fish in the plants' natural environment because, well, we keep fish in the tanks. One must assume that the stock of fish in the natural environment is at a level at or below what most of us keep in our tank. So where are the plants getting all this extra CO2?

Just curious.

 

[DAVIDFBT]

From the fish and animals in the body of water. We add extra CO2 to make a plant grow faster, and to control algea. Aquarium plants already have CO2, they don't need extra CO2, but we want them to grow faster, so we diffuse CO2 into the tank.

 

[Ozymandias]

you also have to remember many plants we use have two forms emursed and submerged. so many times thay take CO2 right out of the oxygen. take HC for example it is relatively easy plant to grow emursed while submerged it's a bit harder

 

[Mgamer20o0]

plus many people try to maxims plant growth something that nature isnt trying to do

 

[Notophthalmus]

There are three major sources of CO2 in most water bodies: first and most important is diffused atmospheric CO2, second is CO2 produced by microorganisms digesting decaying matter, and third and least important is CO2 produced by plants and animals as part of cellular respiration. The last two are really the same process, just at different parts of the biological scale.

The water in an aquarium has a small surface area to volume ratio and generally has a dead air space, so atmospheric diffusion is limited; surface agitation can help this, but still atmospheric CO2 may be relatively low in an aquarium environment.

Most aquarists do not allow large amounts of decaying matter to build up in their tanks; however a healthy mulm layer could conceivably boost CO2, as could a good substratal layer of leaves. I don't know if anyone has tried to measure the effects of these in an aquarium.

The fish and plants in your tank do provide a small amount of CO2.

As was mentioned, CO2 injection is not necessary for plant growth. It is used by people who want jungle-like tanks, love gadgets, or have problems with algae. You can grow quite lovely aquatic plants with no outside CO2 source.

 

[Notophthalmus]

sorry, double post