Koi are domesticated Oriental fish that are also known as Japanese carp. It's important to know about the living habits of koi to keep them healthy in your pond. Besides daily maintenance, you will need to keep pets and children out of the pond to sustain the chemical balance. Most importantly, you need to prevent algae infections that could harm your koi.
Collect any waste, algae and debris from your pond with a mesh net. Submerge the net to the bottom of the pond so that you can remove all loose materials.
Remove up to one-quarter of the water in the pond using a water pump or a large bucket. Place chicken wire in the pond to keep the koi on one end if you are using a pump.
Remove the koi with a small fishing net if there is a distinct rotten smell in the pond after you've removed some of the water. Place the koi in a small children's pool full of non-chlorinated water.
Drain the pond completely using a pump or bucket. The smell is most likely due to algae stuck to the bottom of the pond. Spray the algae with a high-pressure hose and remove it using latex gloves.
Take all of the rocks in the pond and place them in strainers. Wash the rocks thoroughly in warm water over the sink. If there is algae still stuck on the rocks, scrub it off with a sponge. Once they are clean and dry, place the rocks back in the pond.
Add new non-chlorinated water to the pond. Slowly pour in the water using a bucket. Make sure the water adjusts to the temperature appropriate for your koi. The temperature of pond water for koi is typically 40 to 50 degrees. Once the water is ready, put the koi back in the pond.