Though there are a lot of factors that go into caring for a koi pond, the most important maintenance you can do is frequent water checks using a koi pond test strip that checks the water for dangerous conditions.  In addition to regular pond maintenance costs, you’ll also need to winterize your koi pond if you live in a colder area.

When deep cleaning your koi pond, transfer fish to a clean, uncontaminated container at least one foot deep, like a large bucket, tub, or kiddie pond. Fill the container with their existing pond water to avoid shocking them, and place the container in full or partial shade. When it’s time to reintroduce them into the pond, slowly add the new water to the container before adding the fish and container water back into the pond.

Like pools, ponds can be a safety risk, so they may increase your homeowners insurance. Be sure to let your insurance company know if you build a pond on your property—they may have safety requirements in order to keep your premium from increasing. 

You have several options for your pond by getting your yard ready for the winter. You can winterize your koi pond by ensuring it’s at least 5 feet deep so it doesn’t freeze completely, installing a pond heater or aerator and having it run at all times, and installing a deicer if temperatures are dangerously low for an extended period. You can also choose to shut down your pond for the winter by removing all the wildlife in it and bringing it indoors, cleaning out the filter and pump, and then covering the pond with a tarp.