Glass Harp Tuning
A glass harp is tuned by adding water into each glass until reaching the desired pitch. By varying the water level the pitch changes in the same way a string sounds when applying different tensions. The water levels can be easily determined by using a chromatic instrument tuner. The pitch of every empty glass should be higher than the note assigned to it. By adding water the pitch will go down, the tuner will help find the exact amount of water. A small pump is useful to take water out when too much is poured.
Marking the water levels on each glass may be useful to tune quickly without the tuner, but will not be accurate. Its always best to use an instrument tuner or by ear. In some situations the levels can change, tuning on a flat floor or a slope requires different amounts of water. There are also some slight variations with different water temperatures.