The Floating Plant Dilemma
Either you love or hate them, but few people can deny that floating plants add a sense of calm and beauty to the waters' surface. They come in many shapes and sizes, and each has its growing requirements. For this article, I will talk about the three I am most familiar with and some of the issues and or problems with each.
The first floating plant on the list is duckweed, which is considered a pest plant that sometimes gets introduced accidentally for the most hobbyist. This plant can be beneficial but can quickly become out of control. Duckweed has two problems, the first being it's tiny and harder than other varieties to clean 100% out of the aquarium once established. The second is it grows crazy fast. It is easily giving algae a run for its money. This fast growth is sometimes used by hobbyists to control algae as duckweed will compete for the extra nutrients in a tank as it is easier to remove than some types of algae. Duckweed can also be used as a food source for some fish and can be created in specific kinds of fish food. For example, I use duckweed as extra goldfish food and a supplemental fertilizer/compost in my garden.
The next plant is one of my favorite and staple in the hobby. Frog Bit is a medium-sized floating plant with a much slower growth rate than duckweed and is easier to control. The plant has a dark green leaf and grows well in most aquariums as long as it has good lighting. Like all floating plants, it will eventually take over the water surface, which needs to be monitored if you keep other plants in the tank as it will reduce the amount of light to other plants. The roots can also get quite long over time, depending on the substrate of the container. Frog bit does not like to get wet, so avoid using in the tank with waterfall filters unless you have a way of keeping it from the filter.
The last plant pictured above is dwarf water lettuce, which is similar to Frog Bit but has a soft velvet texture to the leaf and a bit of a lighter green. Again it needs good lighting and a slow-flowing tank away form splashing. It grows about the same as Frog Bit but is a larger plant, so the same concerns about blocking light.
I did not go into plant care detail above as all have similar requirements. Good lighting is a must as many of these plants can also be used outside in ponds. I used 6500K led light on all my tanks that contain floating plants. Second, these plants feed on nutrients in the water column, and dosing may be required if the plants are not getting enough nutrients from the tank. This can be especially true if the tank is a new setup. Now, this is something I have learned over the years. If you want long roots, a suitable substrate can also be used as the plants will send roots down, seeking out the extra nutrients. The longer roots can be an issue as the plants will not move around, reducing the water flow in your tank.
Other issues I have encountered with floating plants are duckweed can easily clog up filters and intakes. Floating plants in general if grown thick can reduce the amount of surface agitation, reduce tank light, and can cause trouble for plants planted in the substrate.
Overall, I love having floating plants, but they are work to keep them looking good and keeping the tank healthy. If you plan on having floating plants remember they are not a plant you want to forget about, and if you have certain types, you may have to reduce the number of plants weekly to keep the tank healthy.