Impact of Low O2 on plants

[Mike1971]

I wanted to ask for some advice on O2 levels with CO2 injection. I have only been doing planted tanks for a few months. Since I started I have been focusing on getting 30 PPM+ of steady CO2 and haven't paid attention to O2 levels at all. I originally set up my Fluval output about 6-7 inches below the water surface to reduce the loss of CO2. When I set up my new CO2 system on my tank I gassed my fish to near death. Luckily I caught it in time and used a power head with a piece of hose over night and they are all fine. I have read a few threads about people running air stones at night, and was wondering if people can give me feedback on this. Right now I moved the filter output to about 3 inches below the water surface to create some surface agitation, but no air stone yet. I am using EI dosing on both CO2 injected tanks, and the plants seem very happy with excellent growth and minimal algae issues. I am thinking that since the plants use O2 at night, it can only improve the overall health of the plants. Any advice would be greatly appreciated, I'm interested in hearing about peoples set ups, and how it effects the plants. Thanks.

[Tug]

This is a fast and dirty clarification, but plants respire 24/7. (http://library.thinkquest.org/C004535/aerobic_respiration.html) The Krebs cycle (old school) (http://en.wikipedia.org/wiki/Citric_acid_cycle) functions day and night.

In daylight, during photosynthesis, the Calvin cycle (http://en.wikipedia.org/wiki/Calvin_cycle) converts CO2 and water into the energy used during cellular respiration.

Photosynthesis and Respiration (http://www.youtube.com/watch?v=JEnjph9miK4)

Animation: How the Krebs Cycle Works (http://www.science.smith.edu/departments/Biology/Bio231/krebs.html)

[Tom Barr]

Plants do not use much nor need much O2 at night.
Fish etc are much more sensitive.

I keep good current, that way whether there's high CO2 or not, there's always high O2.

Regards,
Tom Barr

[Biollante]

Hi,

Your critters will critters will die before lack of O2 has a significant effect on plants. :gw

Calcium deficiency is a greater affect on O2 use (respiration) in plants.

A good read on the subject from our inimitable Tom Barr and the best selling Oxygen in the Planted Aquarium, http://www.barrreport.com/showthread.php/1678-Barr-Report-Newsletter-Oxygen and the entertaining Calcium’s role in Aquatic Macrophytes, http://www.barrreport.com/showthread.php/1282-Barr-Report-Newsletter-Calcium.

Biollante