Aeration is essential, especially in the winter, so keeping an aerator in the pond throughout winter is a good idea. As you remove your pumps and other pond equipment, move the aerator to a more shallow part of the pond and run 24/7. The aerator will help oxygenate the water and keep a section of the ice open. When the surface freezes completely, there is no way for the gases created by the breakdown of organic material to escape. The water cannot oxygenate, and the fish and plants can suffocate.

When the water temperature drops, fish become less active because they are cold-blooded. Their bodies and metabolisms slow down, requiring little food and oxygen until the water warms back up in the spring. The bottom of your pond (if it is deep enough, so it doesn't freeze all of the way through) is actually the warmest part. Fish will stay at the bottom, hardly moving, throughout the winter.

Generally, if your pond is at least 24 inches deep (unless you have large koi), your fish can overwinter in your pond. If you have larger fish like koi or live in an area with severe winters, your pond may need to be even deeper (48 to 60 inches) to avoid freezing. You can overwinter your fish indoors by keeping them in a temporary storage tank with aeration.

Tropical and floating plants that are native to areas with mild winters won't be able to overwinter in a freezing pond and will need to be moved inside. Hardier plants can be moved to the deepest (and warmest) parts of the pond until spring. How you overwinter your plants depends on where you live and the plant's hardiness.

TIP! If you’re disposing plants, make sure they’re not invasive or prohibited in your area.