The water manometer is useful to provide a visual representation of the air pressure in the bag for what we call "steady blowing". Ideally the water level in the manometer won't bounce up and down too much while playing the pipes, but even world class professionals will have some subtle variation. At this point I'm just happy if the water doesn't shoot out the top of the contraption between breaths.
I'm finding that there are two phases (all Arm or Arm+Diaphragm) during four steps of blowing the pipes:
- Transition from Arm to Arm+Diaphragm
- Blowing in
- Transition from Arm+Diaphragm to Arm
On a related note, I've started to hear the tuning of individual notes on the chanter against the drones. I can't yet tell by ear if the chanter note is sharp or flat relative to the drones, but I can hear when that note is off pitch. This is something that I learned about at Davidson Scottish Arts Academy earlier this year; when tuning I should be aiming to tune the instrument to itself. When tuning, listen to the chanter notes against the drones and adjust as needed. I'm a slow learner, so I needed to learn what to listen for first, then it took me time to recognize what I was hearing was what I was listening for.