Adding plants to your koi pond can be very beautiful but at the same time they can realy complicate things. Here is why:
If you place shelves in the pond to support the plants and the shelves are less than 2 feet deep, you risk the chance of loosing your koi to predators. Even if the shelves are deeper than 2 feet below the water level you may still have a problem. If when you place a potted plant on the shelf and the top of the pot is less than 2 feet from the pond surface a blue heron may wait until a fish swims over the pot and then strike, pinning the fish against the plant pot.
Most water plants do not like water movement so you cannot use jets in the pond. Therefore, most of the leaves that fall in the pond will sink to the bottom before they reach the skimmer and may have to be netted out by hand.
Often times new plants will have parasites on them so you will need to treat them with potassium permanganate before you introduce them to the pond.
If parasites do get into your pond you will need to treat the whole pond. Most chemicals used to treat for parasites in koi ponds are toxic to plants. This means you will need to remove all the plants while you treat the pond. Additionally, you will need to treat the plants separately before you return them to the pond.
One of the most effective ways to combat string algae in a koi pond is to increase the salt level in the pond to .4%. This is not an option when you have plants in the pond because, most plants cannot tolerate salt at this level and will die.
Once koi get to be 12 inches or larger they begin to eat most plants.
Most pond plants begin to die back in the fall and create a real mess in the pond.
Koi can hide under the pond plants and this can create a potential problem. If a koi gets sick and begins to isolate itself, you may not notice it until it is too late. Plus, if you need to catch a koi for any reason it can be a real challenge catching them among all the plants.
Some people will argue that you must have plants in the pond because the plants are necessary to consume the nitrates that build up in the pond. That would be true if it weren’t for all the algae that naturally forms in a pond. A healthy pond will normally develop a inch layer of green algae on all the inside walls of the pond. This algae, which feeds on nitrates just like pond plants do, is usually more than sufficient to keep the nitrates at a safe level.
A pond with plants in it can be very attractive, but so can a well landscaped pond which has beautiful plants surrounding it, yet with none actually in the pond. Tom Holder (owner of Koi Care Kennel) built this pond with the Advantage System on it and with no plants in the pond. He has a healthy pond that is both beautiful and very easy to maintain.