Stacy from Longview , Tx writes
The rate of Crystal Blue Copper Sulfate is 2 1/2 to 4 lbs per acre foot..Unfortunately Crystal Blue Copper Sulfate is toxic to koi. We do not carry an algaecide or any other products that are safe to be used in koi ponds at this time. We would recommend that you contact a koi pond supplier in your area or possibly your local cooperative extension office for advice on what products to use.
Answer last updated on: 03/10/2020