Cleaning the bottom of a pond is mostly a matter of personal taste. If you don’t mind the natural look of a little sludge and murk on the bottom, you can simply leave it in place until it builds up enough to reduce the volume. For a backyard pond with no fish in it, this could take years. Fish ponds do need annual cleaning at least to reduce the amount of waste trapped at the bottom. This is true even if you’ve installed a complete bottom drain and filter system. Drains and filters allow you to go months or even years between cleaning, but eventually fish ponds need dredging so that the fish don’t run out of room to swim.
Murk and muck in a planted pond is a benefit rather than a problem. This sludge may not look nice, but it’s full of valuable bacteria that work tirelessly to keep the water naturally clean. If you plan to clean out a natural or wildlife pond at least once a year, aim to do it over the winter or in late fall/early spring. It’s not as comfortable for getting wet as the summer, but you’re less likely to disturb any wildlife using the water.
