Hi all,
So if we encourage high oxygen levels in our non co2 tanks via surface agitation it would make sense that bacterial breakdown of rich soil sediments would be maximised. Some of the Co2 produced in this manner would/could still be utilised by plants before it has a chance to reach atmosphere? Or would we reach a point where co2 is off gassing faster than it is being produced. Surely the plants would still get some of the co2 produced via bacterial activity?
They will, this is the situation you deal with when you work with the re-mediation of organically polluted water (commercial aquaculture, sewage treatment etc), here you have huge BOD, and concurrently a large production of CO2. Work on
Eichornia has shown that the addition of floating macrophytes can turn a lagoon from a net CO2 producer to a net CO2 sink. (<"
Floating Aquatic Macrophytes Can Substantially Offset Open Water CO2 Emissions .....".>)
The more CO2 you have in the water, and the larger the surface to volume ratio (gas exchange surface) is, the faster CO2 will equilibrate with atmospheric levels. Because oxygen is much less soluble than CO2, if you have an organic rich substrate you really need a large gas exchange surface, or you run every risk of asphyxiating your life stock at night.
Diana Walstad (in <"
Ecology of the Planted Aquarium">) has figures from Barko & Smart (1983) ("
The effects of organic matter additions to.....") for the production of CO2 from added sources of organic matter, but the authors found that the growth of submerged aquatic plants was reduced by this carbon addition, although this didn't effect plants that were emergent to the same degree.
You can have water supplies which are naturally carbon dioxide enriched,
<"and they tend to have luxuriant plant growth">, even if they are in low nutrient situations.
Are we talking about CO2 in gas form or all kind of carbon based compounds that can be consumed by plants?
Scientists make a distinction between the CO2/HCO3- which are "Dissolved Inorganic Carbon" and other carbon compounds "Dissolved (or Total) Organic Carbon" (DOC or TOC).
High levels of TOC usually suppress aquatic plant grow, although some of this effect is likely to be to do with the lower levels of light in tinted water.
cheers Darrel