My many thanks to Robert Hudson of AquaBotanic for his several
clarifications.

After a successful plumbing exercise in creative misapplication I've
got the unit perking along on a shakedown run now.

I'm using a Hagen 402 powerhead on it now so the flow through it.
Even with the Hagen throttled down all the way to about 60 gallons per
hour, the flow rate is still 20% over the recommended maximum. You
can see those poor ole CO2 bubbles hangin' on for dear life. Tomorrow
we get an itsy bitsy power head.

Now, what should I expect to see in the unit? Let's handle the
bonehead issues first: Are the bubbles supposed to run up or down the
spiral? At 15 bubbles per minute (the manufacturer's initial
recommendation) what should I see after about an hour?

I'm checking the PH every other hour and have the setup on a timer in
phase with the lights. I'm also running an airstone when the lights
go off just in case.