photoperiod: O2 pearling and O2 string

The "bubbling" on the right picture is occurring when the plant has some damage, my hidrophilla pinnatifida is always doing that after I trim its stem

 

When plants are growing they are producing oxygen. That oxygen is released into the water, and immediately dissolved in the water. But, if the rate of release of oxygen is greater than what will dissolve immediately in the water it forms a bubble on the leaf surface. A still higher release of oxygen will cause a stream or streams of oxygen bubbles to rise from the leaf surfaces. If the water is nearly saturated with oxygen, the bubbles will form faster.

 

My plants pearl and stream after WC. Is it caused by elevated photosynthesis from high CO2 content in new water, or just gassing out compressed air in new water?

 

I think I understand where you’re going with this. In vascular plants, gas is released via stomata, pores on the leaf surface, not so much through the cell walls. The rate that induces streaming would depend on the gas pressure, size of the pores, and saturation of the water. Tissue damage is also a common cause. I’ve noticed when mine do that it is almost always from the same location each day, from some damage or defect I presume.

Maybe this helps:
http://www.biology-pages.info/G/GasExchange.html

 

After I sprayed H202 on algae, there was lots of what I think must have been false pearling. It diminished over 24 hours. I was surprised by it and intrigued by how H202 interacted in the water. Pearling is fascinating. I hope I get to see some in my new tank.