I could try the laser sometime and see what it does. The testing that I have done does shows that the DO level increase away from the nozzles so that implies that oxygen is staying in the water column even away from the area of the nozzles.
The ceramic stones are cool. One thing they don't mention is how much power that devices uses. It needs both a fairly large water pump and some kind of air pump strong enough to force the air through the ceramic. They did mention that it was treating an area 100 square meters. That's usually large enough for most areas...but not very large for an ocean!
I'm not sure why no one else has made this but I would speculate it was the cost to make it. Most venturi's are a simple 1 piece. (A standard 2-part cavity mold with 3 side actions). This design is two parts which makes it more expensive to produce and assemble. It also looks like most on the market aren't really designed for efficiency...they just whipped them up so they could sort of work. When you're injecting soaps, chemicals, and fertilizers, they usually just regulate it with valves to adjust the flow.
