Planted FW Theory

Hey Guys,

I posted this question on a planted FW community web site but no immediate answer. So I thought I would hear what you guys think. Having experience in reef aquariums really help raise your level and direction of thinking beyond the average FW methodologies IMO.... Here's what I posted:

Hi Guys,

Can some of you gurus please comment on my theory below.

First a bit of context:

We know that plants during the day time take up CO2 and release O2. And during night time (or artificial darkness) will release CO2 and take up O2.

We know the benefits of dosing CO2 and some guys switch off the dosing during the evening and if you really want to be fancy, use a probe and pH monitor to control a solenoid valve to keep you pH more stable.

Now my theory is this with all other factors being ideal: If I have two tank e.g. my display and a sump of almost equal size. During the day, the display's lights are on and the sump is in a dark cabinet or room. At night, the display's lights go off and the sump's lights go on. In the sump I have more or less the same volume of plants. Now surely, in this scenario, one would not want to dose CO2. The plants from the one tank will feed the plants from the other tank CO2 and oxygen.

Please any comments will be welcomed.

 

Well, I'm no biologist, so I've no idea whether plants release as much CO2 as they absorb, but assuming that they do, there is still no way that the system will remain in equilibrium in terms of CO2 production and consumption.

Gaseous exchange will occur at the air-water interface, and thus your system will be constantly losing CO2 overall. For this reason, I believe you will still need to add CO2 to keep levels within your desired range.

 

The reactions are balanced i.e. 0ne CO2 molecule produces one O2 molecule during photsynthesis, and vice versa during respiration.

My understanding of the reason dosing CO2 in planted FW tanks is that it is to produce an excees of CO2, thus improving photosynthesis and plant growth.

Your idea in theory should work as in the day the excees CO2 released by plants in the "dark" will be consuemd by those in the "light".

I just don't know if the CO2 produced by the plants will be enough to produce a significant effect, compared to dosing CO2.

Nice idea though. Why not give it a try.

 

You guys confirmed my suspition thanks. Damn, I never really thought I would be able to get away without CO2. Those units are just so damn expensive.