For those in the old way of thinking...18KPa equals 2.6 PSI and 2000L/min equals over 70 CFM of volumetric air flow.
With that said, a max pressure rating of 2.6 psi only gets a diaphragm diffuser down to depths of 5 feet of water and that is neglecting any line losses or pump efficiencies. Typically, the air flow at a max pressure rating dwindles to about nothing. You do not need anywhere near the 70 CFM for the diffusers I am familiar with (most diffusers require 1 to 3 CFM). Most pumps run terribly inefficient when their pressure rating is pushed towards it's limits. The exception is the piston pump or the general category of Positive Displacement Pumps.
Disclaimer...I do not have much experience with blowers and have never heard of anyone using this type for pond aeration. I would advise you to look into Rotary Vane or Diaphragm air pumps for your shallow pond. Chances are, a diaphragm pump for your 3 to 6 foot depths will be the most affordable.
I'd love to learn more about the blower you linked. Can you post a pump curve for it?
Will you be using a bubbler/diffuser? If so, What kind? If not, what will be causing the water movement?