Never sit a pump on the bottom of a pond, that is because it can drain
your
pond.Just a piece of info

Everyone should add a sump-pump float cut-off to their pond. I know we did
and it's great. When we leave we just put a bubbler in the pond and if
anything happens ... no worries. Pond will drain half-way and bubbler will
keep fish alive. They aren't that expensive and you just plug them in
between on the power cord kind and they cut the power if the water level
drops.