29 dKh is solid output number. Unless you have like a MaxiJet on full blast with no ball or gate valve, then the reactor will produce more. Coralline is likely your biggest consumer - you can use pincushions to keep it down 6x18 is not that big, but it should get you more. Maybe you have a 8x30, or the like, in your future.
Second chamber does not do anything, really, unless you have just a ton of unused co2 leaving the reactor - this only really happens when people use pH controller and it turns on/off a lot and dumps a bunch of co2 every time it turns on.
I like to keep my dKh around 25, so 29 is fine. You can probably go up to 40 and be OK without melting the media, so you could also turn the bubbles up just a touch.