Really depends upon what kind of cleaning device you have - spray ball or rotary spray jet and how tall your tank is. We run a number of tanks from 100HL through to 400HL.....
For our 200HL BBTs we have a 7.5kW pump rated at 18m3/hr @ 42m head. But your spray device might need more.... We have another cellar that runs Toftejorg rotary spray jets and this requires around 6 bar pressure at the spray, and is a bloody big pump (11kW or something similar to that).
So it really depends on your situation.....
1) determine type of cleaning device to use.
2) consult with spray supplier about flow/pressure required to clean your specific tank (give them a drawing, usually helps).
3) add to this pressure the static pressure (height) of your tank to end up with final duty point (flow @ pressure). Remember 100kPa = 10m roughly.
4) Consult with pump supplier. They will select the best pump for the duty.... and of course, a slightly bigger pump with a VSD corrects all sins.
Hope that helps.