Aquarium Floating Plants. Pros and Cons

Aquarium floating plants can be the key to making your tank a success. So, if you are completely new to the planted tank hobby, or maybe have not kept plants before, this article will be a great start for you.

Even though floating plants in the aquarium are extremely beneficial (for example, they provide additional filtration, cover, oxygenation, aesthetic value, etc.), there are also some downsides that you need to know about.

Without further ado, let’s see in detail the pros and cons of aquarium floating plants and why would you want to add them in your tanks.

Pros of Floating Plants

• Filtration:

We should never forget that our tanks are closed eco-systems. Therefore, with time, our tanks accumulate wastes (animals waste, detritus, food leftovers, dead leaves, etc.), and floating plants play a huge role in keeping aquarium water clean.

They absorb metals, chemicals, and other pollutants that can be harmful to our shrimp, fish, crayfish, etc. Using Floating plants is perhaps the most cost-efficient and environmentally friendly way to provide extra filtration for your tanks.

Floating plants will bring down ammonium, nitrate, and phosphates at extremely high rates because they use all these chemicals to produce their proteins and grow.

Here comes the most important part – the efficiency at removing waste products depends on how fast they grow. If something is not growing fast, it does not need a lot of food. Luckily, most aquarium floating plants are fast-growers.

Having these plants in the tank will let you reduce the frequencies of water changes. In some cases, their role can be so important that their unique form of chemical filtration allows achieving the true balance where you do not have to do even water changes!

You can read more about it in my article “No Water Change Tank?! Top Offs vs Water Change”.

 Some floating plants can even be an indicator of the toxins. For example, if there are lots of nutrients in that water, Duckweed turns to bright green. The darker color and long roots of the plant usually mean that water does not have problems with water quality.

Summary: Floating plants are great natural filters. They use their well-adapted roots in providing biological and chemical filtration. They absorb waste created by tank inhabitants and other detritus from the water thus keeping the water clean and free from potentially harmful bacteria.

• Aeration:

Floating plants are also an excellent natural way to aerate the water in the tanks. They have unlimited and constant access to carbon dioxide (CO2) that they use for photosynthesis and growth accordingly.

As the floating plants undergo photosynthesis, they also convert CO2 used by your fish or shrimp back into oxygen, which in turn improves water quality.

Fish and shrimp absorb the dissolved oxygen directly from the water into their bloodstream through the gills. According to the studies, the amount of oxygen needed varies from animal to animal. For example, most fish species, crabs, and shrimp require minimal amounts of oxygen of at least 4-6 mg/L). If it drops below this level, it will cause a lot of stress that may lead to death.

Therefore, it is absolutely crucial that sufficient oxygen levels should always be maintained in the tanks. We need to keep oxygen as close to saturation as possible. Add live plants to the aquarium and use an aeration system.

Note: Some fish species, such as Bettas and Gouramis, are capable of breathing air.

Summary: Aeration is one of the main functions of floating plants when introduced into the tank. They will play a beneficial role by providing extra oxygen to the tank.

• Cover and Breeding Ground:

Another direct effect that floating plants have on fish and shrimp is that within such aquariums they tend to feel more secure with something above them. Basically, it means that they are less worried about being predated upon and then more likely to come out of hiding and roll around and swim happily within the tank.

This is especially important for dwarf shrimp because they cannot fight back and occupy the bottom of the food chain and they know it.

So, if we provide areas of dense planting, we will give our shrimp more chances to survive and breed. This is one of the main rules if you want to keep shrimp in a community tank.

Summary: Floating plants provide cover/shade for fish and shrimps. These plants act as shelter and hiding place for tank inhabitants.

• Feeding ground:

Lots of floating plants have an intricate shape or well-developed root systems suspended in the water column that will be used by fish and shrimp as a feeding ground.

For example, Water lettuce with its dense, hairy roots or Guppy grass with its complex structure will be an additional place where they can also find bits of debris that have been trapped in there. It is also a great place for the growth of biofilm, which is an ideal first food for newly hatched fry and shrimplets. 

This is the place you will see a lot of shrimp and fish grazing on. Shrimp enjoy hanging upside down on them. Floating plants work excellent with powder shrimp food like Bacter AE.

Summary: The structure of the floating plants often acts as a web, it catches all the free-floating particles. Therefore, it creates a natural feeding ground for the fish and shrimp.

• Algae control:

Another great benefit of floating plants in aquariums is that they help keep algae at bay. We should never forget that the planted tank is never free of algae. Algae growth is a natural occurrence in any tank.

Floating plants do not have roots anchored in soil, therefore, they draw all their nutrients directly from the water.  That is why their algae reducing properties are directly linked to their ability to consume nutrients from the water column since algae feed on them.

Incorporating floating plants into your planted tank will inhibit the growth of algae as well.

Of course, floating plants will not eliminate all algae from the tank. But they will definitely help in this never-ending battle. The algae growth will be significantly lowered and it will not be as aggressive.

Summary: Under favorable conditions, the plants can successfully out-compete algae for the available nutrients in the tanks, so the proliferation of algae can be checked.

• Shade:

Floating plants will create shade that can be a good way to filter lights if you have plants that do not need it (for example Java Fern, Amazon Sword, Marimo Moss Ball, Anubias, etc.). In addition, by reducing light getting to the tank, we also slow down algae growth.

Shrimp and freshwater snails will be especially glad. Since they are primarily nocturnal animals.

Summary: Floating plants will reduce light penetration and create shade that can be important for low-light plants, shrimp, snails, and some fish.

For more information, read the article “Top 10 Low Light Aquarium Plants. Pros and Cons”.

• Aesthetic Value:

Most floating plants are attractive and can add great aesthetic value to your tank. These plants will not only serve as a decorative means but will create a natural-like look in the tank and you will definitely love it.

Just keep in mind that aquascaping requires a fair knowledge about the plants and hardscape. In some styles, floating plants can never be used. For example, the principles of Iwagumi aquascaping does not tolerate chaos in plants. However, if you want to create Jungle aquascaping, floating plants may be a good choice for you.

Summary: Aquarium floating plants are great natural decorations for the tanks.

• Prevent Fish From Jumping:

Once floating plants cover the surface, it will reduce the chances of fish from jumping, when you do not have a lid.

• Maintenance:

Unlike submerged aquatic plants that require regular trimming, in most cases, it is way easier to control floating plants. Just scoop them out when you need to reduce their number. They are easy to remove when get too overcrowded.

• CO2 and Light Undemanding:

Floating plants usually do not require any fancy lighting because they will always get more light than other plants regardless of the system.

The same can be said about CO2. They do not need CO2 injections because they get CO2 from the air. 

• Serve as Food:

Some floating species have tender leaves and quite high in protein. For example, Duckweed species have an average of 37.0% of crude protein, therefore, it can be used as a food source for fish, shrimp, snails, crayfish, crabs, etc. There are many recipes on the internet. 

• Floating plants vs Crayfish and Crabs

It can be very hard to keep crayfish or crabs in a planted tank. These animals are not plant safe. They will try to uproot and eat everything until they turn your beautiful tank into a wasteland.

However, floating plants will be a good choice for freshwater crab and crayfish tanks. They simply won’t be able to get them, so you should have a problem.

Cons of Floating Plants

However, in spite of all the advantages and benefits, there are also some downsides of adding floating plants to our tanks. So, let’s take a look at them and how we can deal with them.

• Fast growth/ Overgrowth:

This is the most common problem you will face while growing floating plants in the tank. Because of their rapid growth rate, they will try to overrun the tank very quickly.

Solution: You need to create some kind of barrier to prevent the plant from spreading all over the tank. For example, it can be an air tubing strung across the top of the aquarium.

Tips: You could always go with less invasive plants like Dwarf water lettuce, Amazon frogbit, Water sprite, etc.

• Water Flow:

In the wild, most floating plants are a natural part of most water environments like lakes, ponds, slow-moving rivers, swamps, etc. They do not like turbulent water. Therefore, if there is a strong current in your tank it can negatively affect them.

Fast water currents might damage the plants especially their long and delicate roots. For example, Dwarf Water Lettuce will get smaller even in gentle water flow.

Solution: The solution to this problem includes either reduction of the flow or using a floating rope or tube to divide the surface area and keep them there.

• Shadowing:

Reduction of light penetration can be also bad if you have other plants in the tank that prefer moderate to high light. Floating plants create a dense mass if left unattended, thereby preventing light from getting to plants at the bottom of the tank.

Solution: Ensure to always trim floating plants and dispose of the cuttings properly so that it doesn’t block the light.

• Entanglement:

Some floating plants have very long roots. With time they can entangle with decorations, other plants, or even clog the tank filters. Depending on the plant species, it may become a nightmare.

Solution: proper maintenance.

• Nighttime Oxygen Depletion:

When the lights are off, all plants in your tank stop taking in CO2 and producing oxygen. On the contrary, they also start breathing oxygen and emitting CO2.

Of course, plants produce more oxygen when they consume but … our aquariums are very complex eco-systems. We can have other variables in this “equation”.

For example, algae, beneficial bacteria, and other photosynthetic organisms also consume oxygen. In addition, when something dies in the tank, the process of decomposition also requires significant amounts of dissolved oxygen.

Unfortunately, people often do not know that or simply underestimate it. In heavily planted tanks CO2 levels can rise significantly, while the oxygen levels drop off.

Solution: Do not rely solely on plants as a natural way to aerate the water in the tank. Use airstones.

• Suppress other plants:

When these plants are allowed to grow unchecked, they can take over other aquatic plants as well. In most cases, floating plants will easily outcompete submersive plants for nutrients.

Solution: Regular trimming and/or fertilizer application will help to replenish nutrients in the tank water.

Important: If you keep shrimp in the tank, I would highly recommend reading my articles:
How Copper Affects Dwarf Shrimp
Shrimp Safe Plant Fertilizers
The point is that copper (most fertilizers contain copper) is extremely dangerous to the shrimp. 

Some other problems you might experience with floating plants:

• Sometimes floating food gets stuck in it. As a result, when it starts decaying, it can infect the plant. You may see some kind of mold on the plants.
• Floating plants often get stuck on the tank sides as the water evaporates.
• Hard to get rid of some plants (like Duckween) if you decide you do not like it anymore. This is not the plant that you can scoop with the net and forget about it.
• Although floating plants are amazing filters, there is a flip side to the coin. When plants die they should be removed quickly before they start decaying and producing harmful toxins.
• Floating plants often have softer leaves compared to other aquatic plants, therefore, they are most likely to be eaten by fish.

Aquarium Floating Plants
Pros	Cons
Harbor beneficial bacteria	Overgrowth
Absorb toxins	Do not like water flow
Produce oxygen (during day time)	Lower oxygen (during the night)
Absorb CO2 (during day time)	Give off CO2 (during the night)
Provide shade for low light plants and animals	Can shadow plants that require more light
Provide feeding ground for fish and shrimp	Too greedy for nutrients. Suppress other plants.
Algae control	Entanglement
Provide cover and breeding ground for fish and shrimp	Food can be stuck be in it
Aesthetic value
Prevent fish jumping
Maintenance
Can be given as food
Great for crab and crayfish tanks
Do not require good lighting
Do not require CO2 systems

In Conclusion

The addition of floating plants will benefit your aquarium tremendously. They are an essential part of a successful fish or shrimp tank. Therefore, all benefits of having them far outweigh the added maintenance. In addition, floating plants are often pretty hardy and can also thrive in tanks without CO2 injection, and only require minimal care. These are a lot of positives; hence I would definitely recommend them to anybody.

Related articles:

Top 7 Floating Plants for Beginners
Top 7 Nano Aquarium Plants
Top 5 Plants for Your Shrimp Tank
Top 10 Low Light Aquarium Plants. Pros and Cons
How to Remove Algae with Plants
Advanced Guide to Planted Tank Lighting.