Use equation: Pressure = density x depth in the fluid x gravitational field strength. We know the in increase in pressure will be the difference between the Final Pressure (at 1.7m) and the Initial Pressure (at 0.5m). Initial Pressure = 1030 x 0.5 x 9.8 = 5047.0 N/m^{2}. Final Pressure = 1030 x 1.7 x 9.8 = 17159.8 N/m^{2}. Increase in Pressure = Final Pressure - Initial Pressure = 17159.8 - 5047.0 = 12112.8 N/m^{2}. N/m^{2} is aslo known as Pascals (Pa). If you are unsure about the units of pressure use the units of the other variables in the the equation to work out the units. (I can explain using whiteboard).