You do not use DO to measure CO2.

O2 levels are correlated with plant growth.

So say a tank with one CO2 method produces say 110% saturation of O2 at a given temp at 8 hours after lights are "on".

The same tank with CO2 mist produces this same level after 3 hours of lights on and then rises to 140% at 8 hours after the lights are on.

Note, this is the same tank, flow characteristics, just one day you do the normal CO2 method, then the following day the CO2 mist method.

That difference in the O2 levels and the timing is due to the CO2 mist effect.
As long as the nutrients levels are non limiting(eg: EI dosing) and light are the same in both cases, then the rather large change in O2 production by the plants is due to CO2.

Plants grow based on light, CO2 and nutrients.
There's plenty of water obviously so that's not considered.

Tank changes between the light/nutrients/plant biomass/current/temp are minimal in the same tank between one day vs the next day.

You can run a control to a see if you wish there as well.
I know what the control does and it tends to stay pretty stable in terms of O2 production difference in 1 single day, they do not change much.

so if you change the CO2 method between one day and the next day and see a huge jump in the pearling and O2 levels, then that is telling you that's very likely the CO2.

O2 meters measure just that, not other gases.
O2 is the best measure aquarist have of actual plant growth althougnh dry weight and a very accurate scale would be nice and correlation of wet/dry weight sand plant parts etc would be nice and nutrient extractions etc.

See the "Phytometer" MS word doc here for more info.

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So using this same method with the O2 meter: remove say 70% of the tank water and not expose the plants to air. Save this same water. Add back to the tank. Measure O2 levels.

Next day do the same thing except remove 90% of the tank water and expose the to the air. Wait 5-15" min mist with some water to prevent dessication. Refill with tank water. Measure O2 levels afterwards over the same time frames(not one discrete point, rather, several for both treatments).

I had 28-52% increase for O2 for the CO2 mist method and about 40-60% for the air exposure treatment. That's a lot more growth increase than folks normally ever see.

That's why mist causes too much growth and too much pearling for many folks.

Formation of O2 bubbles also forms on the top portion next to light where photosynthesis occurs 1st in larger tanks . If it was mere degassing, we'd see bubbles everywhere, but I do not only on the plants closest to the lights and then with time, the plants progeressively farther and farther from the light source.

The plants are exposured for 1 hour and are misted till the refilling neat the top and less so near the bottom.

So is it due to the light distance or the air exposure?
I'm not sure but it seems reasonable to suggest that some of both. How much pearling growth will we get out of a ceertain time of air exposure?

Seems like a little for little exposure.
Or a lot for a longer peroid.

That sounds reasonable.
Without doing a lot of measurements, it'll be hard to say.
Even then generalizing would be tough.

Still, try this exposure to air for say 15" minutes and watch the tank.
Try it 2x a week for 2-3 weeks and see what happens to the tank's health.

It'll shoot through the roof.

My goal here is two fold:
Look at CO2/how the gas phases might be of use to us and to help folks with potential CO2 and algae issues get rid of it.

I noted that Cladophora and other species fo algae took a beating and stopped growing etc and some died off as a result of this treatment in a friend's tank.

It'll not help the algae, so it's worth a try and see the effects.

I trust most folks here can tell the difference between pearlign and degassed bubbles.

I'm not going to bother explaining this to other folks out side the BR. I just do not have the time.

Regards,
Tom Barr