With short tubes you will not see this.
With long tubes, there becomes a pathway for hydroxy exiting the tubes to run downward along side the tube entering back into its bottom.
With short tubes, the water will not become Completely Milky.
With Long tubes, there becomes a path way, the gases get circulated to the bottom and the water quickly becomes hazed from top to bottom. With long tubes, hydroxy is recycled. With short tubes, hydroxy is not recycled. The effect can be seen with a tube of 9 inches in height. It is possible the longer the tube, the more the recycling. Untested at this point.
The pathway in which hydroxy is pulled down along the side the outer tube is visible.
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