Blimey, that lobelia has done well
With ponds it is down to personal choice. The idea behind switching off pumps is that you try to minimise the cooling of the water. If you pump water from the bottom of the pond and it returns via a waterfall then it may cool the water too much if it's really cold.
My pond has the pump switched off because the fish don't need it. When it's cold they lay near the bottom and slow their metabolism, so pollution isn't a problem. They don't get fed from the end of October (or sooner if it's cold) till the water stays over about 10c. Some feed their fish but change foods to one that's more easily digestible. All I really do is make sure the water doesn't freeze over.
My pond is over 4ft deep and some of the goldfish are over 20 years old now.