We have a 1960s rectangular pond (1.2 by 2.5m by who knows how deep) with irises, water mint and one water lily. Only one third has "open" water - the rest is full of plant. With the hot summer the water level has dropped allowing me to see what's going in. I've used a saw to remove about 1/3 of the vegetables (sawing off 15cm sqaures which were about 30cm deep with root and soil). I don't know if I should clear more (I know there are lots of frogs and we have lots of newts in the water end obviously). It doesn't need to be a pristine pond but do I need to remove the 20-30cm of silt in the bottom as well ? And should I wait until winter to do this ? (I've got full arm rubber gloves but I can imagine it would be nicer to do today when it's 20C not when it's 5C).