I think a few things here might prevent some misunderstanding and doubt.

1. Make sure you can tell the difference between good vigorous plant growth vs mere bubbles on the plants. You should see better growth, less algae and importantly, longer persistent growth.

2. The other thing I've done and I know some of you have as well: knock the bubbles off after a water change. Wait 15-30 minutes, then look for bubbles.

3. I did 2# with the test hair grass tank. hat's the only plant in there, it does very Tell, no algae issues etc. You see a little pearling, not much, the plant really does not express a great deal and biomass in the tank is just the mat surface layer only.

I've been doing #2 for clients for many years, I do not like the look of bubbles on the glass, I like a nice clean look when I leave and have the plants growing like weeds. I always wipe the glass/acrylic down right away when I begin to drain the tank, before the water is all drained out, so that surface is clean when the water is filling later on.

I also fluff the tank good after and during a water change, Real good initially, get any detritus out of the corners, any muck, organic matter that should not be there out of the tank and netted up etc.

After refilling, I tend you swish a net around to get any leaves that might be loose, caught in the healthy plant beds/groups, any algae or muck of any sort.

Then I clean any bubbles that form and wipe the front of the glass and off to the next client I go.

I've stayed around and watched the bubbles form after this.
No bubbles reformed on the glass. Bubbles reform on the plants closest to the light first(10-20 minutes). Then progressed down into the tank.

Typically after removing/pulling up the organic matter, disturbing the substrate, O2 levels can plummet. Removal of the muck is good, after there's very low drain on the O2 due to bacteria trying to decompose all this excess muck.

This might play some role in tank's pearling better as well. Organic dissolved matter also plays a large role. I'm one of the few that discusses it.

Amano gives COD levels, which is a nicer, easier to measure parameter than BOD.
I have not done any, but I can predict they'd be much lower after a large water change and I'd be right 99/100 times.

A weekly sum total graph versus a single parameter(who knows when that measure was taken?) can tell you a lot more so please be critical on such data.

The other plausible argument for the bubbles afterwards if you do not have a DO meter/O2 test kit: The plants leaves act like a sponge with the gases, taking them all in and then releasing then slowly after wards.

Well, think about this...........
Now if it takes say 5 minutes to soak in the gas, how long does this plant keep bubbling off the gas?

1 hour? 4 hours? 8 hours of light?

Plants can take in a fair amount of gas and they store O2 in their aerenchyma for their roots, then any excess is piped out.

Algae reduction also suggest something else besides air alone is going on here also.

Many folks notice their tanks pearling like mad after a water change.
Now try this: see if you can stop or stunt this pearling via nutrients or CO2.

**Now you need not harm the plants over the long term either here**.
Just a day or two of no CO2 ought to do it.
PO4 deficiency will greatly reduce pearling also after about 1-2 weeks without much stress to the plants, some GSA and other issues might occur but not that much. Do the water change and note the difference. Give it about 4 hours, see anything happening?
You might aseea little pearling, but likely not that much.

Now, after the 4 hours, add some KH2PO4 after starving the plants a bit for PO4.
Wait 1 hour, now look?
What a difference.............

You may also use one single group of plants that normally never pearls etc, that you have troubles with etc to explore this rather than the entire tank.

I think the notion I am trying to show folks: we can amplify growth better/further/get more pearling/more O2 levels.

Is this a must for the hobby?
No!

Can it help folks and help the basic understanding of algae and plant growth?
Yes!

Is it a good clue that you might not have enough CO2 when the dramatic difference in pearling from the water change day vs the rest of the 5-6 days of the week you do not do a water change?
I think it does and can be generalized as such.

Regards,
Tom Barr