Do you have fish in the pond, if so, how many,
what kind are they and how big are they?

Fish is your consideration if you can turn a
pump on and off.

Few fish, small fish and you can turn off the pump.
Large fish, lots of them you may end up with dead
fish in the morning.
Plants in the pond go from making oxygen in the
day to *using* oxygen at night.
Turning off the pump just adds to the oxygen debt
over the night hours.
Few small fish can deal with it.
Lots of large fish can not.
Hope that helps!

kathy :-)
www.blogfromthebog.com