New O2 meter

Tom Barr

Staff member
Jan 23, 2005
Well, I finally lost my mind and bought a 2000$ O2 meter.

Because I'm obsessed about O2 as a parameter to measure the intensity of plant growth and also to measure closely the levels of O2 as they influence fish health and behavior and the relationship with CO2.

Both the O2 and CO2 meters have LDO or LCO2 sensor units.

This means they do not consume any CO2 or O2 and they are not influenced by any pH, KH etc.

The membranes last for about 1-2 years before they need servicing.
Much better and more accurate than anything else.

The measure of NO3, PO4, K+, etc is fairly easy and straight forward for us and for most research. However, if you get really super low or you want to measure the dissolved gases, then it gets hairy.

So being obsessed about the last real problem parameter makes total sense.

If you add CO2, then you want to be able to accurately measure it and be able to relate that to patterns we see.

I can measure CO2 mist hypotheses and also measure the plant's response in terms of growth by using O2 measurements very accurately and at the same time.

The other cool thing: both units will data log each measurement every 15, 30, 45, 60, or 1, 2, 4, 8, 24 hour intervals. I can set it and leave it and then come back a week later and download the data.


Tom Barr


Junior Poster
May 5, 2005
mist method

i havent been on here in a while and maybe you covered this but did you get any conclusive data comparing mist method to non mist method with actual numbers ie: you can get 10 more ppm with mist over non mist with all other parameters equal. just curious about this.


Lifetime Charter Member
Lifetime Member
Jan 24, 2005
Sacramento, CA
The advantage of the mist method was never so much that it was more efficient in the use of CO2, but that it was more effective in helping plants to grow well. I doubt that, for a given CO2 flow rate, you get any greater concentration dissolved in the water than with an external reactor. But, I don't think there is much doubt that the plants grow more vigorously, as seen by the pearling, and as measured by the dissolved oxygen content of the water, than with the reactor. And, that is the measure of "efficiency" that we should be most concerned with.

Tom Barr

Staff member
Jan 23, 2005
And the nice accurate measure of O2 allows me to quantify and measure this relationship.

I have no way to knowing if the gas phase makes to the plant's stomates or as dissolved forms.

So that part will likely remain a mystery for sometime...............

But as Vaughn mentioned, the effectiveness is hard to ignore.
You do get clear differences in the growth(as measured by O2 production from the plants), there's no argument or debate about that.

Some can make a stink, but if they do not measure the CO2 and O2 accurately, they really cannot say anything because they have not measured it to begin with:rolleyes:

Still, some like to be wind bags I guess.
Arm Chair Aquarist...........

Another idea I came up with as to increased growth: the microbubbles break up the boundary layer between the leaf and the surrounding water. This allows more gas and nutrient exchange.

A control for this would be using N2 gas along with the same CO2 ppms in the control and treatment tanks, then measure O2 production.

If the difference between O2 ppms are significant, then I have something other than the boundary layer causing increased growth. Perhaps more than one thing(such as gas phase and something else I've not thought of yet) or the micro bubble gas allowing faster O2 exchange out of the plants etc.

If the differences are not significant, then the boundary layer effect is not
the cause in the growth differences.

Something else is causing the increased growth. Maybe CO2 mist in the gas phase.........does not prove it though, but does leave the potential for this being a cause, whereas the other would likely rule this idea out, and the effect was due to boundary layers.

So either way, we know more and will get somewhere.

Unlike Mister Wind Bag......................

Tom barr