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Planted Aquariums Basics from Philosophy to Practice

Planted Aquariums Basics from Philosophy to Practice
From Setup to Sustainability: A Deep Dive into Aquatic Gardening and The Ecosystem Philosophy of Planted Tanks

Planted aquariums are awesome and anyone can create and maintain their own little aquatic paradise with a simple understanding of the plant-first philosphy that makes the different from traditional fish tanks. Learn the difference between simply adding plants to a tank and creating a thriving aquatic garden where plants and fish flourish together. Philosphy aside, discover how simply changing your mindset can turn any aquarium into an endlessly fascinating ecosystem. Beyond their beauty, a planted aquarium can profoundly improve your mental health and offer a welcome ecape from our hectic world. Whether you're new to aquariums or looking to enhance your setup, this guide has all you need to create your own underwater oasis.


Defining Planted Aquariums - Not Just Fish Tanks with Plants:

Planted aquariums transform the hobby of fishkeeping into both a science and an art form, focusing on creating ecosystems where plants are the main feature. These aren't just tanks with fish and water that happen to have plants in them; they are carefully balanced ecosystems with plants at the forefront. The design, equipment, and upkeep of these aquariums are all centered around supporting a thriving plant life.

Planted aquarium with hardscape, plants, fish, and sand
A planted aquarium is a habitat where all the living things interact and support each other. It is a whole far greater than the sum of its parts.

In these setups, the choice of animals, such as fish and shrimp, is based on how well they fit into this plant-heavy environment. The goal is to select species that are not only happy in this setting but also benefit from the lush vegetation.

To support this plant-first approach, specific equipment is chosen for its ability to enhance plant health. This includes specialized lighting, filtration systems, and CO2 injections that cater primarily to the needs of the plants. In turn, these plants create a healthy and vibrant environment for the fish and shrimp to flourish.

By prioritizing the balance and interdependence of plants and animals, planted aquariums offer a beautiful, natural slice of life within the confines of your home. Rather than a cage for fish, the tank becomes a vessel containing a living, functional natural habitat in minature.

Can a planted aquarium improve your personal well-being?

Planted aquariums are not just visually striking; they also play a significant role in improving the physical and mental health of their owners. The peaceful scenery of an underwater garden can help calm the mind, similar to the effects of spending time in nature.

Woman doing yoga next to a planted aquarium
Like yoga, keeping a planted aquarium can improve your mental well-being and encourage mindfulness

Having an aquarium with plants and fish provides a soothing experience. Watching these serene scenes can lower stress and anxiety. It offers a form of mindfulness, helping you take a break from the stress of daily life. Research supports the idea that planted aquariums can lower blood pressure, reduce heart rates, ease depression, and decrease stress hormones.

The benefits of planted aquariums are substantial, impacting both your physical and mental health in positive ways. Here's a brief summary of their advantages:

Effect on Wellness


Stress Reduction

Watching the serene underwater world of a planted aquarium can lower stress levels, offering a calming effect similar to nature therapy.

Improved Mental Health

The care and maintenance of a living ecosystem can provide a sense of purpose and accomplishment, boosting mood and combating anxiety and depression.

Enhanced Focus and Mindfulness

Engaging with a planted aquarium encourages mindfulness through focus and attention to detail. Observing and caring for your tank can be a grounding ritual, fostering a sense of purpose and fulfillment.

Increased Creativity

Designing and nurturing a planted aquarium can stimulate creativity, as it involves artistic expression in aquascaping and problem-solving for ecosystem balance.

Educational Value

Maintaining a planted aquarium teaches about ecology, biology, and chemistry, offering hands-on learning experiences about the natural world.

Air Quality Improvement

Plants in aquariums can contribute to improved air quality by increasing humidity and potentially reducing pollutants, creating a healthier indoor environment.

Aesthetic Enhancement

A well-maintained planted aquarium can beautify any space, adding visual interest and a touch of tranquility, enhancing the overall living or working environment.

Social Interaction

Aquarium hobbyists often share experiences and knowledge, fostering community and social interactions, which can be beneficial for emotional well-being.

Watching fish and shrimp in a planted aquarium can be a mesmerizing experience that has the power to improve your mood. This natural aquatic setting offers a healthy and engaging alternative to screen time after a long day at work or school. Hours may fly by as you watch fascinating creatures navigate through a peaceful and vibrant underwater world.

A planted aquarium is like a window to nature, providing many of the same benefits as spending time outdoors, all from the comfort of your living room. It's much more than a space for fish—it's an investment in your well-being. Whenever you need a moment to relax, reset, and ground yourself, your aquarium will be there to provide a temporary escape from the exhausting, fast-paced world we live in.

The Ecosystem Approach: A Fresh Perspective

Understanding the difference between a planted aquarium and a simple fish tank with plants is crucial. A planted aquarium aims to be a miniature version of nature, carefully crafted to emulate the intricate relationships found in untouched aquatic ecosystems. In this setup, plants are much more than decor; they're the foundation of the ecosystem. They play vital roles in controlling water chemistry, oxygenating water, purifying it, and offering shelter to various aquatic species. This plant-focused approach significantly influences how we manage the aquarium—from choosing lighting that supports plant growth to selecting substrates that promote healthy roots, and even adjusting water conditions to meet plant needs.

Planted aquarium with driftwood and light rays
A successful planted aquarium should be as much like a natural habitat as possible so the fish don't even know they're in an aquarium...

In a planted aquarium, plants are chosen not just for their looks but for their ecological benefits. Fast-growing plants deter algae growth, use up fish wastes. Floating plants provide shade and comfort for fish, and carpet plants create striking underwater scapes while purifying the water. This creates a dynamic, nearly self-regulating ecosystem where every organism, from the tiniest bacteria to the most prominent fish and plants, plays a critical role.

This method invites aquarium enthusiasts to think like ecologists, focusing on the ecosystem's long-term health and stability. It's a deeper, more engaging way to interact with your aquarium, encouraging a thriving plant life that supports a diverse aquatic community. It's an excellent opportunity to experience scientific concepts firsthand, transforming abstract ideas into something tangible and interactive.

At its core, a planted aquarium celebrates the interconnectedness of plants, animals, and microbes in aquatic ecosystems. It's a miniature tribute to nature's complexity and beauty, achieved through thoughtful planning and care. This approach not only enhances the visual appeal of your aquarium but deepens your connection to the natural world. Embracing the intricacies of a planted aquarium can be immensely fulfilling, offering a blend of aesthetic beauty, scientific learning, and ecological harmony.


There is a nuanced but simultaneously vast distinction between planted aquariums and aquariums merely hosting plants. This rather important division makes “fishkeeping” and “aquascaping” very different in terms of practical considerations, ecological dynamics, and aesthetic aspirations.

Some of the most important differences between a planted aquariums and conventional aquariums with live plants can be summed up by the table below:

Planted Aquarium

Aquarium with Plants

Primary Focus

The plants, which are key to maintaining the ecosystem to support animal life.

Fish and other aquatic animals, with plants more as an afterthought.

Plant Density

High; the aquarium is densely planted to create a lush, natural environment.

Moderate to low; plants are used sparingly or for decorative purposes.

Substrate Type

Specialized substrates that promote plant growth, rich in nutrients are chosen.

Often standard gravel or sand selected for aesthetics, not specifically designed for plant growth.


Moderate to high-intensity lighting to support the growth of a wide variety of plants.

Low to moderate lighting, sufficient for basic plant survival and viewing.

CO2 Supplementation

Often required to promote robust plant growth, lushness, and to support the high plant density.

Rarely used and generally not necessary for the types of plants kept.

Filtration and Flow

Designed to balance the needs of plants. Focus is on water flow to distribute nutrients and CO2 evenly without upsetting them. Plants assist with biological filtration.

Focused on maintaining water quality for fish, with biological filtration being prioritied. Water flow is based on the needs of the fish.


Regular pruning and care of plants, along with standard aquarium maintenance which can be reduced by abundant plant life.

Primarily focused on fish care, with minimal attention needed for plants. Should be performed routinely to ensure the health of fish.

Aquatic Life

Selection often considers the needs and compatibility with plants.

Primarily chosen based on the preferences or needs of the fishkeeper.

Ecosystem Approach

Designed to mimic natural aquatic ecosystems closely. Plants care for the fish.

May not closely replicate a specific natural environment. Care of fish is mostly through filtration and upkeep.

Role of plants

To create a thriving, lush, underwater garden that provides essential services such as waste detoxification.

To decorate and enhance the living space for aquatic animals.


To create a balanced, self-sustaining ecosystem for all inhabitants.

To keep specific fish as pets.

Discus fish with some live plants in fish tank
The discus fish are clearly the focus of this aquarium. Though it has some live plants, they are secondary and contribute little to supporting the massive bioload of the fish

Fundamental Differences

Planted Aquariums: These are intricately crafted ecosystems where plants are central, influencing both aesthetics and biological harmony. Plants in these setups have needs that are significantly different, often the opposite of fish. Ideally, plants are so prolific they neutralize the effects of a large animal population. The focus shifts to managing light, CO2 and nutrients because the abundant plant life not only produces ample oxygen for the fish and shrimp but also absorbs more waste than they generate. Every element, from the substrate and lighting to filtration and CO2 systems, is chosen with the plants' welfare in mind. Thriving plants, in return, create a healthier habitat for the fish than we could ever hope to manually provide. In these aquariums, plants are not just decorations; they play a crucial role in the ecosystem, enhancing water quality and offering shelter to fish and invertebrates. By nurturing the plants, aquarists enable them to naturally care for the animals.

Aquariums with Plants: In these setups, plants are mainly ornamental, adding to the tank's visual charm but not essential to its ecosystem. The primary focus is on meeting the animals' needs, which can demand considerable effort and time. These aquariums often overlook the specific requirements of plants, resulting in less diverse and vibrant plant life. While the plants do offer some benefits, the needs of the animal inhabitants surpass what the plants can handle. The health of the fish and other animals falls directly to the fishkeeper.


Design Philosophy

Male Cherry Barb Puntius titteya in a planted aquarium
Cherry Barbs (Puntius titteya) are ideal inhabitants for planted aquariums, being small schooling fish. Normally very shy, they become much bolder when surrounded by thick vegetation and display dramatically brighter colors.

Planted aquariums are designed to emulate natural aquatic environments as much as possible. The goal is to recreate an idealized slice of nature (like an Olmstead park), where plants are not just ornaments but key living components of an ecological web. The plants and their environment are central to the aesthetic appeal of the aquarium and enhance fish and shrimp by placing them in more comfortable natural surroundings, thus encouraging natural behaviors and enhancing their coloration. Often the fish are individually smaller but kept in groups. The aesthetic focus is often on their collective and how they interact with the environment around them. No species is emphasized in isolation but rather as part of a greater whole. The planted aquarium fosters a deeper connection with nature, encouraging aquarists to engage with their tanks as gardeners and caretakers as much as hobbyists.

Conversely, aquariums that feature plants without integrating them into the ecosystem's fabric prioritize the health and visibility of fish. In these setups, plants, while enhancing the environment's beauty, do not usually receive the same level of care or consideration as in a true planted aquarium, thus limiting their ability to simulate a natural environment - which is often depicted with inanimate decorations. The fish are often larger and more individually distinct as they are the main attraction. They are the aesthetic priority and are often displayed in isolation from the context in which they live in the wild. 

Ecological Balance and Maintenance

Otocinclus catfish on a leaf in an aquarium
Otocinclus catfish thrive in planted aquariums where they will eat algae. They stay very small and are best kept in groups.

Planted Aquariums: Achieving and maintaining balance is paramount. The health of the plants directly impacts the overall ecosystem, influencing water parameters and the well-being of aquarium animals. Regular care, including trimming, fertilizing, and monitoring CO2 levels, ensures that plants not only survive but flourish, creating a stable and self-sustaining environment. The plants in turn provide everything the fish and shrimp need so by taking care of the plants, they in turn, provide for the animals. Fish still need to be fed as usual but they, along with their food become fertilizer for the plants, and slight overfeeding is less problematic. As a bonus, dense vegetation can create a habitat for small invertebrates such as copepods that become an supplemental source of live food.

Aquariums with Plants: Maintenance focuses more on the aquarium's animal inhabitants, with plant care being a secondary concern. While healthy plants can positively affect water quality, their role is less central, resulting in a greater reliance on filtration and water conditioners to maintain an environment capable of sustaining animal life. Whatever plants present are usually insufficient for supporting the entire bioload of the aquarium so the aquarist must tend directly to the fish and their needs.

Aesthetic and Biological Considerations

Planted aquarium scene with moss and vertical diftwood
Rather than considering its elements separately, planted aquariums are about the "whole" - bringing together all the disparate parts into a coherent visual orchestra

The visual and biological goals of planted aquariums versus fish tanks with plants diverge significantly. Planted aquariums aim to create a harmonious, natural-looking scene that mirrors the complexity and beauty of aquatic ecosystems. This often involves intricate layouts, a variety of plant species, and hardscape, each selected for both their roles in the visual tableau as well as their viability and ecosystem function. The plants are nurtured with specialized care and equipment which in turn allows them to nurture others and be the primary visual attraction. 

A fish tank with plants, while still benefiting from the beauty, oxygenation, and nitrogen absorption that plants provide, will probably not achieve the same level of ecological or visual complexity. The focus tends to remain on the fish and the overall maintenance and equipment priorities for the well-being of animals often limit the diversity and density of plant life. They do not have enough plant life for them to be considered vital to the function of the aquarium. 


Starting a planted aquarium is an exciting dive into the world of habitat creation, blending both art and science. In this approach, plants are not just decorative; they're crucial for the ecosystem's health, allowing for a wide variety of species to thrive. When focusing on plants, your fish selection will lean towards species that prefer lush environments, benefiting from the shelter and richness dense plants provide. Smaller fish, generally less than 4 inches in size, are ideal as they visually complement the scale of a planted tank and maintain a lower overall impact on the ecosystem. Despite a narrower choice of fish and shrimp, these species often lead healthier lives in the diverse and naturalistic settings of a well-cared-for planted tank. This underscores the fundamental difference between true planted aquariums and tanks that simply contain plants.


Core Elements of Planted Aquariums

Creating a thriving planted aquarium goes beyond simply filling a tank with water and plants. It requires careful consideration of some core components to ensure the health of the aquatic ecosystem. Many of these are required in virtually all aquariums but their configuration, importance, and purpose can be very different from a fish-centered tank (even with some plants). The most basic building blocks of any aquarium, other than the tank itself, are the substrate, hardscape, lighting, water circulation, and filtration—all of which play crucial roles in the vitality of aquatic plants and the overall balance of a planted tank.

The table below summarizes what the core elements and tools you need for a planted aquarium, why they are important, and how they may from a traditional fish tank:


Planted Aquariums Importance

Fish Tanks with Plants Importance


High priority: Specialized substrates rich in nutrients are crucial for plant growth.

Moderate priority: Gravel or sand suffices for decorative plants.


High priority: High-intensity, full-spectrum lights are necessary to support a wide range of plant growth.

Moderate to low priority: Standard lighting is usually enough for basic plant survival and for viewing the aquarium.

CO2 System

High priority: CO2 supplementation is often necessary for promoting robust plant growth and health.

Low priority: Rarely needed unless the tank contains plant species that require it.

Filtration System

High priority: Must balance mechanical, chemical, and biological filtration without disturbing plant or substrate.

Moderate priority: Focus is more on water clarity and quality for fish health, with less concern for plants.

Water Circulation

Moderate priority: Gentle flow is preferred to distribute nutrients and CO2 without uprooting plants.

Moderate to high priority: Important for oxygenation and preventing stagnation, particularly in larger tanks.


Moderate priority: Necessary if the aquarium houses tropical plants and fish requiring stable, warm temperatures.

Moderate priority: Depends on the species of fish kept; many tropical fish require stable, warm temperatures.


High priority: Essential for providing plants with the necessary nutrients that might not be present in the water. In a tank with fish, I recommend supplementing Iron and Potassium as fish and fish food should provide plenty of phosphorous and nitrogen

Low to moderate priority: Optional, depending on the plant species and their specific needs. Most often, the fish produce enough wastes to fertilize the plants and supplementation is seldom required

Aquascaping Tools

Tools like tweezers, scissors, and substrate spatulas are essential for planting and maintaining layout. Good quality tools can make your life a lot easier.

Not necessary unless engaged in detailed plant arrangement or care.

The Tank

As discussed in detail in another article, a planted aquarium can be established in just about any type of aquarium container though planted aquariums have different standards for sizing and are typically smaller than other types. The shape may also be important with landscape-orientated tanks being easier to start with. Rimless glass tanks are the best option for aquariums around 20 gallons while rimmed glass tanks may be significantly less expensive and more practical for aquariums of 55 gallons or more.  


Often called simply “gravel” in conventional fish aquariums, the substrate is significantly more consequential for a planted aquarium. It is not just an important aesthetic decision but has implications for growing plants and the health of all that live within. 


Not just a bed for plant roots, your substrate is also critical for nutrient supply. Aquatic plants derive essential nutrients from their roots, so choosing the correct substrate is pivotal to their vitality. Some specialty planted aquarium substrates can even alter your water chemistry to be slightly acidic and softer, making it more closely resemble the natural environment of densely planted waterways. This is consistent with the ecosystem ethos of planted aquariums where the emphasis is to replicate natural environments as much as possible. 

Extreme closeup of Eco-Complete planted aquarium substrate
The substrate is an important consideration when creating a planted aquarium

Options range from specialized aqua soils (or “active substrates”), which can provide a rich base of nutrients, to inert substrates used with root tabs or liquid fertilizers to support plant growth and everything in between. Different substrates have different properties which can have a big effect on the health of your plants and water chemistry so choose wisely.

Start with our guide to the details of substrates for planted aquariums for a thorough lesson on why substrates are important, what they can do, and which one is best for your situation.  


Hardscape refers to the non-living elements used in aquariums to create structure and visual appeal, such as rocks, driftwood, and decorative substrates. Though not required in every planted aquarium, these elements often form the bones of your aquascape, providing anchor points for plants and mimicking natural landscapes underwater. Popular hardscape choices include stones like Seiryu or Dragon stone, and wood types like Manzanita or Spiderwood.

Beyond aesthetics, hardscape can influence water chemistry—driftwood, for instance, may soften and acidify water, beneficial for certain plant and fish species. Certain types, such as Malaysian driftwood, will leach tannins, giving the water a brownish tint popular for replicating “blackwater habitats”. However, not all materials are suitable; limestone can harden water, which might not be ideal for all plants and fish especially the types best suited to densely planted aquariums. Moreover, sharp-edged rocks could harm active or large fish.

The selection of hardscape materials should be intentional, with consideration for their aesthetic impact and the holistic environment you’re aiming to create, ensuring both beauty and the well-being of the aquarium’s inhabitants.


Often an afterthought in fish tanks, lighting plays a crucial role in the success of planted aquariums, serving as the primary energy source for the process of photosynthesis. This process allows aquatic plants to convert light energy and CO2 into chemical energy, fueling their growth and reproduction. The effectiveness of this conversion hinges on the availability of light within specific wavelengths, known as Photosynthetically Active Radiation (PAR), which falls within the 400 nm to 700 nm range of the visible light spectrum. Red and blue light within this range are particularly important for efficient photosynthesis.

The intensity of lighting required in a planted aquarium varies depending on several factors, including the type of plants, the depth of the tank, and the availability of CO2. Plants categorized as low-light require less intensity compared to high-light plants, which thrive under more intense lighting conditions. This variance in lighting needs means that deeper tanks, which naturally receive less light, need stronger lighting to support plant life, particularly for growing more colorfully vibrant red plants that demand higher light intensity. Without adequate lighting, plants may exhibit leggy and pale growth, a clear sign of insufficient light.

However, there's a balance to be struck, as excessive lighting without a corresponding availability of inorganic carbon sources can encourage unwanted algae growth. Interestingly, the introduction of CO2 into the tank can mitigate this issue by allowing more light to be used by plants. CO2 supplementation can also reduce the overall light intensity needed for plant growth, allowing for a more controlled and algae-free environment. This balance between light and CO2 is pivotal for cultivating a thriving, vibrant planted aquarium.

Lighting Types

Options abound when it comes to lighting a planted aquarium, each with its own set of characteristics suited to different plant requirements and tank dimensions as summarized below. As of 2024, most people will be best served by some sort of LED-based light.

Lighting Type



Fluorescent Lights (T5HO Bulbs)

Beneficial spectrum and intensity for plant growth. Cost-effective for beginners. Even beam with diffuse effect

Becoming hard to find and may be obsolete. T8 bulbs not suitable for planted tanks

LED Lights

Highly efficient and generate less heat. Can simulate natural lighting conditions. Affordable and widely available. Suitable for growing plants with a variety of spectra available

Less diffuse lighting can create stark effects. Excessively bright LEDs may promote algae growth with low CO2 levels

Metal Halides

Powerful, suited for very deep tanks

Generates significant heat and consumes more energy. Expensive and complex. Generally not recommended unless for specific needs

We recommend getting the best lighting that you can afford - preferably a dimmable fixture if you are not supplementing CO2. The old rule of thumb specifying 2-3 watts/gallon for medium light plants and 4 to 5 watts/gallon for high light plants is meaningless since it does not specify the type of light source or its height above the substrate. It will often cause you to overshoot - as will the “50 PAR at substrate level” rule.

Get a light specifically designed for a planted tank of your size from a company specializing in aquarium plants. High light plants are almost always CO2 starved and their light requirement can be surprisingly low once their carbon requirement is fulfilled. Low-light plants are usually better suited for growing in low-tech tanks because of their adaptability to the low CO2 concentrations in aquariums or the ability to use alternate sources of inorganic carbon (eg. bicarbonate). 

It is impossible to fully discuss lighting without talking about CO2 since the two are linked by photosynthesis. Check out our article discussing the interplay between lighting and CO2 in the photosynthesis of aquarium plants.

Water Circulation and Filtration

Water circulation is extremely important in a planted aquarium, perhaps more so than filtration itself. Good water movement ensures an even distribution of nutrients and CO2, maintaining temperature uniformity, and reducing “dead spots”. Insufficient water flow, especially in a densely planted tank with plenty of vegetation to block moving water, can result in areas of poor water circulation. These “dead spots” can become locally deprived of nutrients and CO2 while accumulating detritus resulting in poor plant growth and water quality.

If using a classic Hang On Back (HOB) power filter, we recommend investing in an inexpensive powerhead to circulate water through the tank better. External canister filters are favored in planted aquariums because they can be fitted with a variety of glass inflow and outflow fixtures called “lily pipes” which not only help guide water current and tackle dead spots but also improves the appearance of a planted tank by eliminating ugly filter intakes.

Lily pipes and dropchecker in planted aquarium
Lily pipes help dramatically with water flow without making it too strong and look great doing it!

Mechanical filtration is recommended to keep the tank clean and detritus from getting out of control, choking plants’ leaves, and feeding algae. Most filters achieve this with no problems.    

While biological filtration is important for breaking down waste products (specifically ammonia into nitrate), it's not as important in planted tanks where plants themselves do a lot of the work. Ammonia is the preferred nitrogen source for plants (not nitrate as frequently stated), and in a densely planted tank with a reasonable bioload, the plants will absorb the ammonia as quickly as it’s produced.

Biological filtration is still necessary because it is much more consistent and can take over in case of a problem. It also hosts a load of other microbial processes. We recommend focusing on biological filtration when selecting media, ideally enough for mechanical filtration as well. 

Chemical filtration, particularly with activated carbon, should generally be avoided in planted tanks. This is because it can remove not only harmful substances but also trace nutrients vital for plant growth. It may be used if medication or other chemicals need to be removed but should not be used in the long term. We recommend avoiding it and even going so far as to remove the carbon from filter cartridges that contain it.


These are not vital per se but for those of us residing in cold climates and keeping a single tank outside of a dedicated fishroom, they are a necessary, if boring, piece of equipment for any aquarium.

The general rule of thumb for selecting an aquarium heater's power is to allocate about 2.5 to 5 watts of power per gallon of water in the aquarium. This means, for a 20-gallon tank, you'd need a heater ranging from 50 to 100 watts to maintain a stable water temperature suitable for most tropical fish.

The exact wattage within this range depends on the ambient room temperature and how much higher the aquarium's temperature needs to be compared to it. For colder environments or larger temperature increases, aim towards the higher end of the wattage range.

Balance your Equipment

In essence, each of these core elements—substrate, lighting, water circulation, and filtration—need to be carefully considered in the context of plants first. They are interdependent, with each affecting the others, and need to be balanced to ensure the overall health of the aquatic ecosystem. A successful planted aquarium requires these components, creating an environment where both plants and aquatic life can flourish.


The Role of CO2

A planted aquarium as dense as this would be impossible without CO2 supplementation. All of these species, including the ground cover requires CO2. With good lighting and CO2, this can be achieved in a couple months.

Photosynthesis requires CO2 and light to make organic molecules such as sugar which stores chemical energy. It is the most important process that allows plants to support entire ecosystems. Without CO2 photosynthesis is impossible and too little CO2 limits photosynthesis no matter how strong the lighting. Sufficient CO2 makes photosynthesis more efficient and allows for more light to make a difference. 

Despite being undisputedly vital for plants, CO2 in planted aquariums is surprisingly controversial. A lot of this is due to the legacy of aquarium CO2 systems being expensive and very complex though that's certainly not the case with our CO2ONE system. Some argue that CO2 supplementation is akin to cheating, but we counter that it simply replicates the conditions many aquarium plants naturally thrive in—waterways rich in CO2.

This alignment with natural habitats is a central element of the planted-aquarium emphasis on creating authentic ecosystems. Indeed, even skeptics once introduced to CO2 fertilization find it indispensable for achieving lush, vibrant plant growth, often becoming advocates. It simply makes too much of a difference to ignore.

Though you can create amazing planted aquariums without CO2, you will be severely limited to a small fraction of the available aquarium plants and it will take a long time. For beginners, CO2 is often the difference between a lush impressive aquascape and constant battles with algae, and, contrary to some people’s beliefs, supplementing CO2 is the easiest way to get started in this insanely rewarding hobby since beginners will be able to grow whatever plants you want, quickly establish a functional ecosystem and have far fewer algae issues.

Unlike natural aquatic ecosystems enriched with CO2 from organic decay and groundwater, our home aquariums have very little CO2 because these enrichment processes cannot be replicated in a small glass box. CO2 levels where many plants are found exceed 10-30 times what they are in an aquarium and many aquatic plants will rightfully struggle. CO2 availability in a low-tech planted aquarium will be even more dire because plants use up the available CO2 faster than it can be replaced by fish or diffusion from the atmosphere. Fortunately, with a little help from artificial CO2 supplementation, we can bridge the gap between the natural world and our home aquariums, ensuring our underwater gardens can thrive to delight us and take care of their inhabitants.

CO2 Fertilization Methods

There are many ways to inject CO2 for beginners including DIY setups that can be a fun project for those who like to tinker. Typically these use sugar and yeast, bacteria, or a chemical reaction between citric acid and baking soda. They are fairly simple to understand and set up. While they are the most affordable way to boost CO2 levels, they are less consistent and can be more difficult to regulate than pressurized systems and are suitable for only small tanks. Nonetheless, even being able to add a few parts per million of CO2 can enhance plant growth dramatically and a DIY setup is definitely worth a try.

Other CO2 injection methods rely on using CO2 compressed into liquid stored in a heavy metal canister. These range from all-in-one kits using disposable pellet gun cartridges to elaborate custom-designed systems that use canisters heavier than your aquarium. For most, the best solutions are somewhere in the middle. 

CO2ONE regulator on SodaStream Canister with diffuser and dropchecker
Our CO2ONE system (with a SodaStream canister) is fantastic CO2 injection method for anyone. Everything you need is in the picture.

We would - of course, specifically recommend our CO2ONE system which is compatible with any CO2 source (including SodaStream cartridges which last a long time between refills on even large aquariums). Our CO2ONE system is also compatible with paintball canisters as well as traditional CO2 cylinders for those with much larger aquariums. CO2ONE has everything you need to run and monitor CO2 and allows for the reliability, consistency, and precise control that you’d expect from a professional CO2 solution. It is not only shockingly easy but powerful and flexible - an ideal, dead simple, solution for virtually anyone - a far cry from 20 years ago when CO2 systems were extremely complex, cost thousands, and were less reliable.

CO2 is again, a vast and complex topic that is best suited for a dedicated article so we’ll move on for now.


Choosing Animals and Plants

Selecting the best flora and fauna for your planted aquarium is essential for its success. Ensure your choices can thrive in the conditions you provide. Consider the individual needs of particular species along with their aesthetic and ecosystem function in the context of the whole. The interdependence between different species in context is essential to maintain balance and ensure the long-term health of your aquatic habitat.

Selecting the Right Plants

Every planted aquarium ecosystem starts with its plants. They are the aesthetic focus as well as the foundation for the habitat that you are trying to create. When plants do well, animals benefit, so it is important to select species that can thrive within the environment of your aquarium and can contribute meaningfully, or do not hinder your other organisms. You can also work backward by selecting species you want to grow and determining their requirements. Either way, make sure the plants you choose can survive and grow well within your aquarium or they can do more harm than good.

The table below summarizes some aspects to consider and then pick your plants accordingly:


Considerations and Recommendations

Tank Conditions

Assess lighting, substrate, water parameters (pH, hardness), and size.Match plant choices to lighting conditions (intense vs. low-light). Choose plants compatible with your substrate and water chemistry.

CO2 Dependency

Avoid CO2-dependent plants in low-tech setups - they wil be guaranteed to struggle and can even die. With a CO2 system, most plants, including "difficult" ones, will thrive in most any aquarium except some Eriocaulons and Blyxa which need specific water chemistry.

Nutrient Requirements

Ensure compatibility among plant species’ nutrient needs. Most substrates can be adapted to suit plant preferences with the right approach. Given enough light and CO2, shortcomings in your substrate will be much less important.

Growth Rates & Maintenance

Balance fast-growing species with slow-growers based on maintenance preferences. Fast-growers improve water quality; slow-growers add interest with less upkeep. Regularly trim fast-growing plants to promote health, prevent them from blocking light and encourage branching for a fuller, lusher growth habit.

Aesthetic Goals

Decide on a desired look: densely planted, lots of diversity, minimalist, or a mix. Use tall plants for the background and carpet plants for the foreground. Choose plant species with varying leaf shapes, sizes, and colors for visual diversity. Group plants in patches for a natural look, and use "dither" plants for cohesion. My favorite theme utilizes full background plants and carpeted foregrounds for a more complete aesthetic. Integrate hardscape for a comprehensive, living scene.

Animals for a Planted Aquarium

While plants are the central focus of a planted aquarium, the inhabitants of your underwater habitat are still extremely important to its aesthetic appeal, therapeutic effects, and overall functioning. There is nothing quite like watching fish and shrimp graze, swim around, and interact with the plants you have so diligently cultivated. The more content your inhabitants are, the more calming they will be to watch. Pick fish and shrimp that are compatible with the environment, compatible with each other, and compatible with your vision.

Fish and Invertebrates Species: Not all aquatic animals are suited for a planted aquarium. Some fish species, for example, are known to dig up plants or nibble on their leaves. Some invertebrates such as crabs will do the same. Animals not adapted to thick vegetation may be uncomfortable and destructive. Opt for species that are known to coexist peacefully with plants.

Many small schooling fish, such as danios, tetras and rasboras, appreciate the shelter provided by plants and bring a sense of unending dynamism to your display. Other small fish such as gouramis, dwarf cichlids, or killifish are individually fascinating and add more detail and behavioral dimension to your community. The Endler's Livebearer is another favorite though their rapid reproduction can get out of hand.

Choose fish that are individually small so they fit with the scale of the world you have created and do not distract from the greater whole. Similarly, certain shrimp (like Amano shrimp and colorful Neocaridina and Caridina species) are endlessly entertaining and further add diversity to your ecosystem. Some fish, shrimp, and even snails can be beneficial by feeding on algae and debris without harming the plants.

Contributing to the Tank's Balance: The key to a successful planted aquarium is achieving a balance where plants and aquatic life support each other. Select fish and invertebrates that contribute to the health of the aquarium by controlling algae growth and fertilizing the plants through their waste. In turn, the plants help oxygenate the water and provide hiding spots and breeding grounds for your aquatic life, creating a harmonious environment.

Colorful Malawi African Cichlid
Though stunning, avoid fish like this African cichlid whose natural habitat contains very few plants. They can rip up your aquascape, will not be entirely comfortable, and need water chemistry that is incompatible with most aquarium plants.

Choose inhabitants that hail natively from densely planted environments and interact effortlessly with the flora. They will likely also have requirements well-suited to planted aquariums. Avoid species (like African Chiclids) that are accustomed to hard, alkaline water and are awkward with plants. Avoid larger fish as their bioloads may exceed what your plants can handle and look out of place in the context of a detailed, but confined, aquascape. 

Compatibility and Behavior: Research the compatibility of your chosen fish and invertebrates with each other and with the plant species in your tank. Consider the water parameters that each species requires and ensure that there's a good match across the board. Behavioral traits, such as territoriality and schooling tendencies, should also be taken into account to ensure a peaceful and thriving aquarium.


Routine Care and Maintenance

TDS meter measuring water from a planted aquarium
To keep your tank healthy, some routine maintenance will be required. Tools like this TDS meter can be used to check the unseen and determine if you need a water change.

Though we aim to replicate a natural ecosystem, that’s not entirely possible within the very small confines of an aquarium. In addition, a completely natural ecosystem may not be aesthetically desirable and even obscure our view of the aquarium. Luckily, planted aquariums can last for a very long time, as long as you want, and continue to thrive, evolve, and delight us as long as you tend to some routine tasks. Like walking your dog, these can become positive experiences that are stimulating and help establish a healthy routine. 

Nutrient Supplementation

Other than CO2, aquatic plants need a variety of nutrients to grow and even just survive, including nitrogen, phosphorus, potassium, and trace elements. Regularly test your water parameters to identify any nutrient deficiencies and supplement accordingly. Liquid fertilizers and root tabs are common ways to provide the necessary nutrients to your plants. In a tank with a lot of fish eating a lot of food, typically only iron and potassium need to be supplemented and can be done on a fixed schedule as neither are harmful or materially relevant to algae to the extent that even a seldom-performed partial water change can’t fix.

Pruning and Trimming 

To maintain the desired aesthetics, prevent overcrowding, and encourage bushier shapes, regularly prune and trim your plants. This encourages healthy growth and allows light to reach lower-growing species. Remove any dead or decaying leaves to prevent them from decomposing in the tank, which can adversely affect water quality - the ones that remain will contribute toward the nutrients in your substrate and water column. 

Water Changes 

Woman performing a water change for a planted aquarium
Partial water changes need to be performed to keep your aquarium balanced and healthy in the long-term. Keep that in mind and pick a tank size that is managaeable for you.

Due to the biological processes in any aquarium, including thickly planted ones, water chemistry will change over time and water changes are a fact of aquarium life. They are required to maintain a degree of consistency and keep parameters within acceptable boundaries for all the lifeforms that depend on it. Keep this fact in mind when choosing the size of your aquarium, keeping it within what you are comfortable performing a water change on. Perform regular water changes, typically 20-30% every two weeks, to remove excess nutrients and waste that can lead to algae growth. Water changes also help replenish essential minerals and trace elements that plants need to thrive. Larger tanks can go longer between water changes - up two once every two months - while the smallest nano-tanks may need it every week. Even if you can’t do it as often, try and do it when you can and try and keep them regular. Your fish and plants will thank you, often with an immediate growth spurt!

Algae Control

Algae growth can be a sign of imbalance in the aquarium, often due to excess nutrients or light. Some issues can be diagnosed because they cause certain forms of algae. Regularly clean your aquarium glass, substrate, and decorations to keep algae in check. Introducing algae-eating fish or invertebrates can also help control algae levels. Algae is not a bad thing and is an important part of natural aquatic ecosystems, but it can be unsightly, grow on your viewing surface, and even hurt your plants if allowed to get out of control. Leaving some algae for your fish and shrimp as well as for the ecosystem services they provide is a good idea, just clear out what makes sense to you and whatever is growing on your plants. Remember that algae reproduce by splitting so keep the reproductive population low or you'll be more likely to experience major algae blooms!

Cycle Light and CO2

Ensure your plants receive the appropriate duration of lighting each day. Too much or too little light per day can affect plant growth and health, especially in the absence of CO2. Plants need both the light and dark to photosynthesize and grow. The standard practice is lighting your tank for roughly 8 hours a day, with 16 hours of darkness. Consider using a timer to regulate photoperiods by mimicking natural day-night cycles.

Similarly, CO2 injection is only required during the 8 light hours as plants respire like animals at night and consume oxygen. This can help prevent unseen pH drops and make your CO2 supply last three times as long. Usually this can be done with an automatic solenoid valve (like in the CO2ONE system) plugged into the same timer as your lights. If not, consider investing in an inline solenoid to automate this.


TIP: Monitor CO2 concentration with a dropchecker. 

CO2 Drop checkers showing good low and high co2 levels
Dropcheckers will indicate the CO2 content of your water and are essential. Aim for blue or blueish green. Dropcheckers have a delay so wait after you've made any changes.

CO2 is crucial for plant photosynthesis, but maintaining the right levels is a delicate balance—too little and your plants suffer, too much and you risk harming your aquatic life. A drop checker is an invaluable tool for accurately monitoring CO2 levels in your planted aquarium and should be in every aquarium that has a CO2 system. 

A drop checker is a small, liquid-filled chamber that changes color based on the CO2 concentration in your aquarium water. By comparing the color against a reference chart, you can determine if your CO2 levels are low, optimal, or too high.

Using a Drop Checker: Fill the drop checker with the appropriate indicator solution and place it inside your aquarium where it's easily visible. The solution will change color according to the CO2 level: green indicates optimal levels, yellow means too much CO2, and blue signifies insufficient CO2.

Adjust your CO2 system based on the drop checker's feedback. Allow for a four hour delay in responding to changes to be safe. Aim for a consistent green color, indicating that your plants are receiving the right amount of CO2 for healthy growth without compromising the safety of your aquatic life. Your range can be lower, which some opting for blue-green, especially in tanks with moderate lighting.


Conclusion and Summary

Creating a successful planted aquarium involves understanding and managing key elements such as lighting, CO2 levels, and water quality. Proper lighting is critical for plant photosynthesis, which sustains plant growth and supports the aquarium ecosystem. Different plants require varying light intensities, influenced by factors like tank depth and CO2 availability. Ensuring the right balance prevents problems such as excessive algae growth.

Water circulation and filtration are crucial for distributing nutrients and CO2 evenly, while maintaining clean and stable water conditions. Effective water movement can be achieved through additional equipment like powerheads, and choosing the right filter media is essential for removing waste without stripping the water of beneficial nutrients. CO2 supplementation is vital for enhancing plant growth; options range from sophisticated systems to simpler DIY methods, depending on the tank's needs and the aquarist's preference.

Selecting compatible plants and fish that thrive in similar conditions is important for maintaining a balanced aquarium. Routine maintenance, including pruning plants, performing water changes, and managing algae, keeps the tank healthy and visually appealing. Monitoring CO2 levels with a drop checker ensures plants receive adequate CO2 without jeopardizing fish safety. By attentively managing these aspects, aquarists can cultivate a vibrant and balanced planted aquarium that serves as a dynamic aquatic landscape.

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