It started pretty quick. This morning I'm getting 23 bubbles a minute.
Is that too much?

That's probably just about right, depending on how much of it is actually
getting diffused into the water.
I tested it just now, I'm have about 19ppm! Just wondering when it'll slow
down to the point where I have to work another bottle in.

The problem is that when I turn my aquaclear filter down in the
morning when I feed, it stops bubbling and water siphons back into the
hose a few inches, then it has to clear it out again.

Err, that ain't good. It sounds like your Aquaclear is somehow actually
drawing CO2 through the line hose it's on ... if so, your CO2 mix bottle
might collapse. The CO2 should be coming from the hose on its own
(positive pressure).
I posted a message up here asking if putting the hose into the end of the
intake tube of the AquaClear was ok...thinking that the bubbles will be
sucked in and churned by the impeller, breaking them up and storing them
there for a while to absorb more C02 into the water instead of it
escaping...everyone thought it was a good idea and I saw other ppl doing it
too. How would you do it? I could build a reactor..but for now I was just
going to do it the simple way and see how successful I am with just getting
the damn stuff into the water.

Thanx,
Dave.