@ both: if it does freeze over with the water fall on, should i just grab a hammer and break the ice?
@ uh hua: do you stop feeding them when it is 50 degrees at night or day?
The outside temperature really does not have much bearing on when you need to stop feeing your fish!! Invest in a pond thermometer....stop feeding when the water temp drops to 50 or 45dg..not the outside air temp. Also in the fall start feeding your koi and fish food based with wheat germ, this will fatten them up more so that when they are in a hibernation state they wont die sof hunger. I personally try to keep TWO holes open in my pond (600gallons) the reason is that last year with the huge amounts of snow....the surface heater melted the top snow slightly and then refrooze at night creating a bubble of ice over the entire hole/heater not allowing gasses to escape. with two holes....you have a better chance one will always stay open. One hole use a surface heater, scond hole an aeration pump/stone.
also i dont recoomend keeping your pump on for the whole winter ...reason 1 being it isnt economical, 2. your taking the warmest water from the bottom, and moving it to the colder area on top or worst over a waterfall which really will chill the water. A heater and air pump uses a fraction of the electriciy a pump will use.roud: