How to winterize your koi pond

It's time to start winterizing the koi pond. Here's what you need to do now to help fish survive the winter.

Your fish instinctively started fattening up in September. Stop feeding them when pond water dips below 50 degrees. You'll notice their activity slowing down at that time. Their digestive system slows down, too, so continuing to feed them would put them at risk for bacterial infections.

Check filters for sediment buildup and clean them as needed. Drain pumps and pipes, and turn off. Wrap exposed pipes with insulation. Several types are commercially available, or you could get creative and make your own.

Cover the pond with netting to keep leaves out. Otherwise they'll get all slimy and introduce dangerous bacteria to the water. Without a net, you'll have to use a skimmer to remove leaves continuously as they fall throughout the season.

Fish are more likely to die from gas poisoning in frozen ponds than from freezing temperatures, so ice openings are crucial. They allow harmful methane and hydrogen sulfide gases to escape and oxygen to enter.

Although fish ponds should contain at least 500 gallons of water, the minimum depth of ponds is only 24 inches for successful overwintering of fish. If your pond is shallow (less than 3 feet deep), you'll have to purchase a floating heater, which will prevent the entire pond from freezing over. As long as there's a small unfrozen area on the surface, the fish will survive.

If your pond is deeper than 3 feet - most are - you shouldn't need a heater, as it's unlikely the whole thing will freeze over. But just to be safe, check it periodically and gently poke a hole in the ice in the unlikely event it covers the entire surface. Never use a sledgehammer to poke holes in frozen ponds because you'll risk damaging your liner and injuring the fishes' eardrum-equivalent organs.

Bog plants should be moved to deeper water for winter protection. Cut them back first so they don't rot.

In the spring, remove netting and clear away any dead plants, leaves and algae from the pond. Start running the pump and top off with more water if necessary.