So I guess with that modification, it's not the best in the business?
Haha, that's an old design I had, predates them by 6 years.
See the 2-3$ DIY version which looks better on the articel link here:
http://www.barrreport.com/forums/showthread.php?t=11&page=1&pp=&conly=1
image:
http://www.barrreport.com/gallery/showimage.php?i=138
Took me 15 minutes and needs no sponge, and cost 15$ total with new powerhead or about 2-3$ without the cost of the powerhead added. You can make these any size(scaled up larger) or use more than one to suit larger tanks.
You can also use the venturi loop on external CO2 reactors to reduce gas lock and to prurge the gas that fills the tubes later in the lighting cycle.
No one else makes such a loop, probably because I've been the one designing them for many years

Not other folks who see a design, try and copy it, charge 3X the cost. I just show the plans for folks to make it themselves.
Mine also works better.
Regards,
Tom Barr