Koi and Pond Net

SAFE WATER CHANGING
Changing water, and/or cleaning the pond can be disastrous to your koi if you do not do it right. Changing of water should only be done if you experience uncontrollable algae blooms, disease, or other water problems. Koi are very sensitive to removal and water changes, and if proper steps are not taken, they could all die. If you do have to change your water, here are the steps to be taken:

create a temporary environment for your koi, with a filter and an aerator. You can use connected buckets, a hole with painters plastic, kiddy pool, etc.... *Remember! The less space there is, the more aeration and filtration you need.
cure the water in the temporary environment with a chlorine and chloramine remover. Let the aerator run for 15 minutes before introducing the fish.
check the temperature difference between the two environments. If the temperature is 10 or more degrees, let the temp environment set, until the water has adjusted.
carefully net the fish and introduce them to the temp environment.
add a fish stress reducer, such as Stress Kote (c), to the water.
check the fish, and observe them. If they are gasping for air, increase the aeration. If they continue, put the fish back into their original home.
remove all objects from the pond. (rocks, pumps, etc..)
after you are sure the fish are happy in their temp environment, drain the water out of their original home, and spray with water, and continue to do this until it is clean.
fill the pond back up with water, letting the water splash slightly.
cure the water with chlorine/chloramine removers and a stress reducer. *Some new products feature a chlorine/chloramine/stress reducer all in one. Check around before purchasing multiple bottles.
check the water's pH level and chlorine level. If pH registers 6.5-8.0 and if chlorine registers 0-0.1 then it is safe for fish to be re-introduced.
aerate original home for 30 minutes, and circulate by stirring
carefully net fish and re-introduce them into their home. Observe them, and if they start to gasp or die, put them back into their temporary environment, and add more chlorine/chloramine/stress reducer formula to the water, and check again.

If you follow those steps, and do not change the water too often, your fish should stay healthy during and after the process has been completed. But, please remember! Fish do not like water changes and will jump out of their pond, or die.