Chi is sort of a situational thing in regards to visibility. Those who can sense energy, magical or otherwise, can sense Chi visually, seeing it as a sort of bluish-clear aura. As for the moves themselves it depends on the force and nature of the move. A typical monk may attempt to extend his chi with a punch to increase his range, allowing him to 'punch' an object roughly ten feet away from him. The amount of chi this takes is miniscule, and would at most be felt by someone as the air displaces itself in the vacuum left behind by the chi's passage. Another monk, however, might wish to expel his chi about him in a blast-wave of sorts designed to thrust back opponents and knock over surrounding objects. This requires significantly more chi, though it is still not a monumental exertion, and would appear to be a dim blue blast-wave.
The pattern of visible chi intensifies the more powerful the move is, in a spectrum that goes from dark blue to dazzling white, and from dull tones of such to bright as a sun.
For instance, that Geyser attack would have been a sort of teal-blue wave, bright like water reflecting sunlight; moderately bright, and not painful to observe.
