Spring Treatment for your pond or watergarden.
Once the water temperature reaches 60 degrees you need to be very aware of your koi. When the water temperature is between 60 degrees and 70 degrees the risk of disease is high.
The untended watergarden or koi pond will have lots of dead leaves and other debris in the bottom of the pond and in the filters. These dirty area harbor some organisms that can harm you fish.
In the trade, we call this Aeromonus Alley because while the temperatures are in this range the fishes immune system is at its weakest for the year. Koi are very susceptible to Aeromonus at this time. Aeromonus is a bacteria and usually shows up after some other problem happens.
It can be as simple as your fish bumping up against something like a sharp rock or piece of plastic on the side of the pond. A wound is created and the bacteria sets up house. Likewise, aquatic insects like Lernia and Argulus that are like fleas and ticks on our body will create a small wound that allows entry for the bacteria.
The key is keeping the water clean. How you do that is by having good filtration and removing any debris that has accumulated. My flow-through filters get really dirty during the winter and I try to clean them out a couple of times a winter. I also have some bead filters and I clean them every week or two during the entire season.
One of the more important things I do is treat the ponds with potassium permanganate. I like to do this in the cool weather because it is probably easier on the fish.
More later see the PP Protocol 02262008