Supaverm is safe for use on koi only. It will kill goldfish! It is believed to remain in the water after use for up to one month. It will not harm the filter media. Remember to shake the bottle well before use. Treat the pond with 1 ml per 100 gallons. Do not perform any water changes for at least 10 days. Supaverm has been shown to be much more effective when used with a salt level of .3% or higher. For that reason we highly recommend using it with salt. If there are plants in the pond and the use of salt is not possible, we recommend treating a second time 5 days later. It is not necessary to do a water change after using Supaverm.