I can't find much via google on serious 12 volt pond pumps. Are there
any r.p.m readers using one, or know of one that can pump suitable
volumes for use in a 5000+ litre pond?

I'm interested to know the power requirements and feasibility of running
from a car batter charged by photovoltaic panels. The price of solar
panels seems to be dropping all the time, and with energy costs going up
it might be worth looking into.

David