Hornwort & Anacharis
Oxygenating plants like hornwort and anacharis are vital to a pond that doesn’t make use of a pump or filter. I lumped these two plants together for a reason. They are different, yet their benefits are similar. These two plants are the kings when it comes to oxygen production and filtering pond water.
These plants perform the same job as an electric pump and electric filter. They are both hardy and grow quickly during the late spring and summer months. By September/October, they slow down. Eventually, they go dormant for the winter months until the following season. It all depends on how cold it gets during winter.
Both of these plants are very easy to introduce to your pond. Hornwort is simply thrown in and it eventually sinks to the bottom. Heavy rain also helps this process along. Even though it falls to the bottom, hornwort doesn’t actually root.
You wouldn’t know it by looking at an established hornwort cluster. I’ve also noticed that hornwort doesn’t do as well in direct sunlight as it does in shaded areas. It sometimes grows intertwined with the anacharis which seems to help shield it from direct sunlight. This is another good reason these two plants go well together.
Anacharis is an even more productive plant. You can either anchor it to the bottom or just throw it in the pond. Anacharis also sinks to the bottom and unlike hornwort, it does root.
Overgrowth is possible
While both of these plants are great for a natural pond, they can also overgrow. Depending on the situation, you may have to cut back the anacharis or remove some of the hornwort. Sometimes you can have too many plants in your pond.
Anacharis usually roots in the deeper section of the pond. It then grows outwards. It doesn’t always hug the edge of the embankment. While it hasn’t been a problem yet, I do occasionally take hornwort and anacharis out of one pond to add it to another which can use it. Nothing gets wasted. While I’ve never had extra that I had to throw out, I also have six ponds to work with.
Have some to pond plants spare?
If you have only one pond, you may find yourself with extra hornwort or anacharis at some point. You might be able to sell some of these plants to your local pet shop. You can also see if they need snails when an overabundance is available. Mystery and apple snails have value.
There are lots of other oxygenating plants available online. I tend to keep things simple and stick to a general formula. That certainly doesn’t mean that you can’t make a work of art out of your own pond. The possibilities are nearly endless. Don’t be afraid to experiment. At the same time, I would be careful when adding wild plants because some grow out of control.
While I’ve had luck with hornwort and anacharis from the wild, other plants that were accidentally introduced quickly became pests. It becomes more work in trying to remove them. Duckweed is a fine example. I’ve also bought plenty of hornwort and anacharis from online stores when I first started out. It might be a good idea to go that route.
Pests such as water bugs come in on the wild plants. Most species are harmless, while some are beneficial by providing natural food for your fish. On the flip-side, some species actually feed on small fish and tadpoles. I had this experience in my bass pond until they got big enough. The bass eventually wiped out all the problematic water bugs.
How plants oxygenate a natural pond (a basic summary)
Oxygen enters pond water through the atmosphere and from plants in the water. Ways oxygen enters the water by way of the atmosphere include wind and rain. With plants, the primary sources of oxygen come from microscopic algae and submerged plants. In sunlight, these produce oxygen through photosynthesis. This is how hornwort and anacharis release oxygen into the water of your pond.
At night, pond plants remove oxygen from the water by respiration. During the day when the sun shines, plants produce more oxygen than they consume. By this, they provide oxygen for fish, tadpoles and other organisms which need oxygen to survive. Mother Nature provides a nice balance, usually. Why ‘usually’ and not all the time? I was just getting to that. Have you ever heard of a fish kill?
Hopefully, you’ll never experience a fish kill in your pond. Fish kills occur naturally, or by humans by way of chemical exposure. Last year a major hurricane swept through Florida. One of the main rivers in central Florida experienced a massive fish kill. In this case, the cause of the fish kill was oxygen depletion.
Oxygen depletion is the most common cause of fish kills in ponds. This mostly occurs in the summer when warm water holds less oxygen than cool water. The pond’s oxygen demand is greater in warm water than in cool water. When a fish kill occurs, some, or all the fish die.
Large and sensitive fish species are the first to suffocate. Smaller and hardier fish are more likely to survive. Many fish and amphibian larvae can survive low oxygen levels. A fish kill that takes out an entire pond is a rare occurrence.
Oxygen depleting plants
Not all plants are good. There are some villainous plants too. There are some plants that happily steal the oxygen from your beloved hornwort and anacharis. Duckweed is one such offender. I’ve talked about duckweed in other articles on this site so I’ll keep it short. Duckweed is often brought in from others ponds by ducks and birds. If left unchecked, duckweed quickly overtakes the entire surface of the pond. It blocks out the sun for the underwater beneficial plants.
Certain nuisance species of algae follow a similar path. Such algae quickly multiply until it floats to the top of the water. Copious amounts of algae yield the same results as duckweed. One can manually remove duckweed. Control algae with a high-quality product such as Nualgi. Supplement treatment by manually removing the dead algae floating from the top as needed. Being a pond owner keeps one busy.