It's not the stream of bubbles that aerates. Most aeration systems are used to lift water to the surface and at the surface is where aeration occurs. Or some such scientific nonsense along those lines. But I'm no expert, one of the experts can give you a better explanation. BTW until reading this site I thought the same thing that aeration was "forcing" air into the water. Sheesh all the years at looking at the air stone in an aquarium assuming I was jamming the water chock full of good air.

JHAP
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"My mind is a raging torrent, flooded with rivulets of thought cascading into a waterfall of creative alternatives."
...Hedley Lamarr (that's Hedley not Hedy)