that is irrelevant information, as any idiot could run his pump with tap water and screw everything up...
additionnally, I dare you say that "your" pumps are tap water friendly ...
So let's not make assumptions on what pumps are better than others, since we don't know all the facts that led to this or that result...
finally, I'd like to add I've been test running my 2 CSP750 mk 1.5 ( mk1 motor, mk2 housing ) with 2 kinds of automotive coolant fluid mixes ( "Elf" & "Ford - Special Yellow for Hi perf engines" ), both with good results ( 1st with 80% distilled water, 2d with 90% distilled water mix )