ponyrandy - yes, that is the bubble counter. Notice the doorbell looking thing to the left of the reactor ... that is the Fabco 55 needle valve, mounted thru the support panel.
heineken357 - there is another xp3 on the other end of that pipe. The pipe is a common manifold that feeds both xp3's from 5 different points within the aquarium. I can't answer the "how many bubbles" question yet as I only got this tank up and running late on Thursday night/Friday morning and the co2 connected Friday afternoon. I'm running it at 2 bps right now and know I'll have to turn it up some more but I haven't gotten the level set yet.
If you're interested, you can find more info about this tank renovation here: http://www.plantedtank.net/forums/ph...rnal-pics.html