What is this comming out of the plant? (with pics)

Yes the water change saturate the gases dissolved in the water so the O2 cant dissolve and comes out as bubbles. Once the O2 levels go back down the O2 released by the plants gets dissolved right away and you have no more bubbles.
 
wow, i did not know that Rich!!!!!
 
Like Karl said, it usually means there's a puncture; air is leaking from the tissue. It'll stop when the punctured vacuole/s are depleted or the wound is healed over. This steady stream is different from the 'pearling' associated with photosynthesis.
 
Looks like pearls to me
 
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