Rhinos nano. Apps 1/2" diamater. Stem is actually slightly buried into substrate. Return catches bubbles moves down opposite wall, across both , about 1/2 way across bubbles start returning to top. This pic is late afternoon in the starting Co2 about a month or 2 ago with 2BPS, note the DC dark green and almost no drop in Ph. Since then much higher BPS tank looks like soda now.
P.s Thanks for helping trouble shoot
Bump: As a side note. With a darker green DC I get bad algae, so I run it high which helps and my fauna look and act fine pushing it this high
Don't complicate things, simplify them!