Usually, when having an aquarium, you don’t only have fish, you usually also have plants. Plants are sold in fish stores but are they the same as land plants? How do the aquatic plants live underwater? Is it the same as land-living plants?
Aquatic plants utilize photosynthesis but have adapted to the lower amount of carbon dioxide in the water. Aquatic plants will also use nutrients in form of macronutrients (nitrogen and phosphorous) and micronutrients (iron and copper) that they pick up from the water and the soil they are growing in.
Since the water-living plants work almost as land-living plants, can you put land-living plants into your aquarium and expect them to survive? I will dig deeper into land-living plants vs. aquatic plants in this article.
What Are The Characteristics of Aquatic Plants
The characteristics of aquatic plants are that they can live completely submerged, growing under the water but be able to break the surface or that they grow floating in or on the water.
The plants growing in the substrate can usually grow floating too.
That’s because the aquatic plants can take up nutrients through the water, which makes them less dependent on taking up nutrients from their roots as land-living plants are.
Now, some nutrients are picked up from the substrate and the root system but they could also take those nutrients from the water, just as the floating plants are.
Another characteristic of aquatic plants is that they are buoyant.
Since they are buoyant, they don’t need a hard stem to be able to support themselves. The buoyancy will do it for them. So, if you plant an aquatic plant (most of them at least) on land, it will not be able to support itself and it will look really sad laying there on the soil until it will rot and break down.
Every plant uses photosynthesis, no matter if they live under the water surface or over the surface.
One crucial part of photosynthesis is carbon dioxide.
Photosynthesis is the act that plants use carbon dioxide and light energy to produce energy for the plant itself and oxygen that it releases into its surroundings.
Under the water, there is less amount of carbon dioxide than it is in the air. Therefore the aquatic plant needs to adapt to less amount of carbon dioxide.
Aquatic plants are only being able to use some amount of light during the day before it goes to “rest”. This is a part of the adaptation of the lower amount of carbon dioxide inside the water.
If you want to read more about aquarium plants and light, take a look at my article covering just that! You will get a deeper understanding of how photosynthesis works underwater.
The aquatic plants need water constantly. If you keep potted plants at home, you just need to have the soil moist for the most time. If it dries up you will be fine for a while.
But with the aquatic plants, they need to be completely submerged or the soil needs to be saturated for them to survive.
Aquatic plants are more dependent on water than land-living plants are.
Nutrients For Aquarium Plants
Like every living creature, plants need nutrients to survive.
As I have mentioned before is photosynthesis an important part of a plant’s life. One of the most crucial nutrients is therefore carbon.
Carbon is released into the water from the fish and other living creatures in the water. It is also released into the water when organic matter (plants or animals) dies and is broken down in the water.
The carbon is needed for the plant to produce the energy it needs. It’s like the food that you and I need to eat to survive.
Other nutrients the plants need are nitrogen, phosphorous, iron, calcium, and magnesium. These are just a few of many other nutrients.
These nutrients are divided into two groups. Macronutrients and micronutrients.
Macronutrients are the nutrients that plants use the most. This includes nitrogen and phosphorous. These are a major part of the mass of the plant. That’s why these nutrients are important for the plant to grow.
These nutrients are usually released into the water from the fish food that is not eaten. It is also partially released into the water from the fish poop.
The micronutrients are the nutrients that are used in very small amounts. These are mainly minerals such as iron, copper, and zinc.
These nutrients are important for the plant too since it uses the minerals for some of its functions such as produce chlorophyll which makes it possible for the plants to utilize photosynthesis.
The minerals are, in nature, picked up from the substrate and some of them from the water itself. The minerals are released into the water from the rocks in the surroundings.
In an aquarium, you usually have to add these nutrients since no mountains are releasing the minerals into the water.
You can buy these supplements from the fish store.
The plants that are harder to keep are more dependent on these minerals than the plants that are easier to keep.
Plants That Won’t Survive In an Aquarium
Aquatic plants and land-living plants have a lot in common in how they work. But that doesn’t mean you could pick a plant from nature, put it in your aquarium and expect it to live.
In fact, I would not suggest putting any plant that is not made to survive submerged in your aquarium. The risk of the plant dying is big and if it dies, you will get an imbalance in the water parameters when it rots which is risking your whole aquarium.
Some land-living plants might survive submerged but they will not reproduce. That’s because they are adapted to a life outside of the water and are using pollen to reproduce. Under the water surface, the pollen technique is not very sufficient since the pollen won’t be able to spread.
There is less carbon dioxide inside the water too and this is what usually kills land-living plants. They need more carbon dioxide to produce their energy.
“But swamp plants? They live in very humid conditions, aren’t I able to use them in my aquarium?” You might think.
It could work. But they usually live over the surface and just have their roots submerged. Since plants pick up carbon dioxide from their leaves. They are adapted to the conditions above the surface and therefore will probably die if being kept submerged.
You could however have plants growing above the surface of your aquarium with the roots submerged. It could give a very cool look and many aquascapers are using that technique in their aquascapes.