- Getting everything ready for colder weather means cleaning the koi pond and doing a complete water change. After alot of reading and research I finally have some awesome healthy fishes that I just love and adore! Getting the pond ready for fall we are going to try and get rid of as much algae as we can and clean the filters out really good, this sucks as it kills the biological filter built up in the pond but I figure with the next week still being warm we should be good and should give it time to come back. Floating plants: going to throw them all away as none wilk make through the cold weather and then they break down making a even bigger mess in the pond. My pond is about 150 gallons and I have 9 fish 4 koi and 5 goldfish. So let’s hope I can get this all done lol I will be taking all the fish out putting them in a container then before I put each koi back I will give them a 7 minute salt bath just to make sure they don’t have any parasites. Then they will go back into the fresh water!! I add a conditioner to the water to kill the heavy metals and I add about 1 cup of pond salt to the water to help kill any parasites and it’s really healthy for them !