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Choosing a Tank for Your Planted Aquarium

Choosing a Tank for Your Planted Aquarium
What are Your Aquarium Options, Where Did They Come From, and Why Are They Shrinking?

Selecting a tank is the first step toward creating a beautiful planted aquarium and deserves considerable attention. There's a lot of confusing, misleading, badly outdated information out there that can harm your chances of success. This guide aims to make sense of all the dizzying options and anticipate, or avoid unwelcome surprises. We'll also discuss some fascinating background and history about planted aquariums - including why they are shrinking.

Planted aquariums can be any size or shape but some are easier to work with than others - especially for beginners

A planted aquarium, inspired in large part by the "Nature Aquarium" concept, is a tropical, freshwater habitat where plants are as much the centerpiece as the fish or shrimp that dwell within it. Initial considerations should focus on the space needed for the species you're interested in and the specific aquascape you aim to achieve. Tanks vary widely in shape and size, with certain designs more conducive to the intensive growth and showcasing of aquatic plants.

While size is clearly an important consideration, the importance shape is frequently overlooked. Tank proportions will influence lighting, water circulation, and CO2 distribution, all of which are critical to your planning process.

Though most tanks are made of glass, due to its superior optical clarity and strength, choosing between rimmed and rimless tanks is an additional aesthetic consideration. Rimless tanks offer a sleek, modern look that can enhance the visual continuity between the aquatic world and your living space, while rimmed tanks are often more available, less expensive, and provide additional structural support.

This how-to aims to shed light on things that you will want to bear in mind as you decide on the perfect tank for your planted aquarium. Your prerogative lies in envisioning and executing your underwater garden, tailoring it to your unique vision. When making decisions and choosing among options, remember that knowledge is your most important guide and potent tool for avoiding unwelcome surprises.


The Ideal Aquarium Size is Relative

There are no hard rules to define what large or small means in relation to tank size. These classifications are arbitrary and even the consensus varies widely across different genres. Saltwater reefs, cichlid dens, and planted aquariums will have different size standards based on their specific requirements.

Moreover, collective perceptions of ideal tank sizes for planted aquariums have evolved and continue to evolve, influenced by factors such as changing tastes, advances in technology, the growing body of knowledge within the aquascaping community, the introduction of new plant species, shifts in societal preferences, and ever-changing trends in aquascaping.

These trends have significantly impacted aquarium design and maintenance practices, further affecting size considerations. Consequently, a tank size considered small in the context of fish-centric setups, which was the assumption thirty years ago, might now be viewed as large, rendering older aquarium literature less relevant to your situation today.

Plants and other decor can really frame spaces. Despite taking up space, aquarium plants can make space more functional.

Contrary to what one might expect, purposefully adding plants and décor into an aquarium makes physical space more useable so planted aquariums are often functionally larger than their fish-only counterparts. This phenomenon becomes particularly evident with smaller sizes such as a 10-gallon tank, which, despite being considered very small by general standards, can transform into generously appointed environments with the introduction of plants. Through the strategic use of plants and hardscape, you can dramatically improve the usability of the same amount of space.

Just as a 5000 sq ft room can feel disconcerting and cramped for a few people if left empty, the same space, when thoughtfully partitioned and furnished, can comfortably accommodate many more without feeling crowded. In an ideal aquarium, plants act as the partitions and furniture, providing essential structure, defining territories, and creating spatial divisions that cater to the diverse needs of its inhabitants, akin to how walls differentiate bedrooms from a kitchen.

In densely planted aquariums, plants offer crucial hiding spots for shy species like cherry barbs, leading to their increased activity, confidence, and vibrant color display, particularly their cherry red coloration. This architectural role of plants enhances the well-being of aquarium residents by providing a sense of security, affecting their perception of space, and promoting healthy and happy inhabitants.

Beautifully aquascaped planted aquarium with a small school of fish
Densely planted tanks make fish and other creatures feel secure and confident. With all the nooks and crannies to hide in this aquarium, your inhabitants will be much more likely to see the aquarium as their home, rather than a confined space that they want leave in order to find somewhere else that makes them feel more comfortable

Tropical fish often hail from natural habitats teeming with dense vegetation, much like the multitudes of fish that inhabit coral reefs. Plants are "primary producers" that create usable organic material such as sugars from light energy and inorganic carbon (primarily CO2). The creation of a whole lot of something from a whole lot of nothing sets up a domino effect: the abundance of plants leads to an abundance of resources, which in turn fosters rich biodiversity to exploit those resources.

Unsurprisingly, it is these most biodiverse, ecosystems have yielded most aquarium species species. Rreproducing the natural environments of these animals transforms the tank from a mere glass enclosure into a comfortable, functioning habitat.

What Animals Need

Unlike plants, animals move around to find food, escape predators, and find suitable habitats. When these needs are met within the confines of the aquarium, they are happy to stay put. If not, they will be compelled to leave and the confines will become restrictive. The introduction of dense plant life provides the essential safety, suitable habitats, and even live food sources, giving your animals few reasons to want to leave their oasis.

The contentment of fish and shrimp in an planted aquarium that provides for all their needs is a key reason why many aquarists report witnessing their fish breed spontaneously after being introduced to a densely vegetated aquarium. It's as if our aquatic companions are signaling their satisfaction and readiness to start a family in their leafy abode. They feel provided for rather than imprisoned

A Brief Word on Fish Selection

Even for large tanks, we recommend sticking with smaller fish (and shrimp) whose adult sizes do not exceed 3-4”. A single 4” fish will have the same biomass as nearly 20 1.5” fish and 64 1” fish of the same shape (roughly). Your aquarium will likely handle the bioload of larger fish but large numbers of smaller fish look better against the background of a lush underwater garden. They can be kept in larger groups and will look great when schooling (though schooling is a defensive behavior and uncommon once the fish feel safe and accustomed).

One of the most important aesthetic themes in planted aquariums is the exaggerated sense of scale which would only be consistent with smaller fish. Larger fish break that illusion and may look out of place. One potential exception would be angelfish - but we would recommend at least 75 gallons or larger for those.

Big Tanks

Larger aquariums offer an unparalleled immersive experience with their expansive views. The generous dimensions provide ample room for creativity, letting you grow a wide variety of aquatic plants which add depth and complexity to the aquascape without overcrowding.

Large plants prominently displayed or striking hardscape elements, such as driftwood or rocks serve as focal points that help weave a cohesive theme throughout the design. In these spacious environments, the possibilities for creative expression are vast, with plenty of space to incorporate diverse visual and thematic elements to keep your planted aquarium perpetually engaging and mesmerizing.

Large planted aquariums are absolutely stunning!

Large tanks, with the space for more plants, also accommodate more animal inhabitants. Although the fish (and shrimp) most suited to planted tanks tend to be individually small, a bigger tank has the space for larger schools of little fish which can be an unforgettable sight.

You also have the choice of more species, including obvious ones such as Angelfish and Discus, as well as species with specific needs such as territorial dwarf cichlids (for South America) or conditionally aggressive fish like Gouramis. 

German Blue RAMs (Mikrogeophagus ramirezi) actually hail from South America. They are a fantastic choice for a planted aquarium as they are usually very peaceful in a densely planted environment, even in smaller tanks.
A somewhat disorganized and and cluttered layout lacking unity among the difference elements.

On the other hand, a larger, more complex aquascapes can take a lot of time, thought, and work to plan and execute. Because of the sheer volume of plants required, it may be challenging to balance the composition so it does not look disjointed and confusing with too many elements fighting for attention. Consider some tips to create a naturally looking, visually cohesive aquascape.

  • Randomly scattered plants can appear disorganized and unnatural. Focus on a unifying theme, whether around a piece of hardscape, a group of plants, or a single specimen plant.

  • Unified does not mean uniform so make sure to avoid a display that is too monotonous with the same colors and textures repeated so that it becomes difficult to tell the different plants apart.

  • When choosing plant species, consider their color, leaf morphology and size so as to determine what purpose each will serve.

  • Make sure adjascent plants complement one other without clashing or appearing too matchy-matchy.

  • Put plants of the same species together to form patches as they would probably grow in nature.

Include different leaf shapes, textures, and colors in a way that shows diversity but does not appear discordant or overly busy. Use "dither" plants, that would be plain by themselves, to unite more visually distinct species which really stand out. Use the boring plants to connect the louder elements of your composition for a cohesive whole out of all the disparate parts.

While you want to draw some attention to the more striking and distinctive plants, you do not want them all talking over each other. You might not be able to predict which plants look good together beforehand so experiment by placing each near each other before planting them to evaluate how they look. Always keep their adult sizes and colors in mind so that your aquascape does not develop in a way that takes a wrecking ball to the basis of your composition. Remember to place shorter plants toward the front and taller ones in the back to give the impression of depth and fullness. These are some fundamental principles of aquascaping that we'll discuss in detail in another article.

While these concepts should be applied to any aquascape of any size, redoing a large aquarium can be a herculean task so it's more important to get it right.

Bigger is Better Except When it Isn't....

For practical considerations, larger tanks are generally considered more stable and easier to deal with in the long run. They are less likely to fail due to a single error and are less prone to sudden, catastrophic problems because of the sheer volume of water for insulating and diluting a lot of potential issues. Parameters like water chemisty or temperature change much slower than they would in a smaller tank, so you have much more time to notice that something could be causing a problem before those problems make a consequential difference.

Upkeep such as cleaning and water changes can be less frequent since these systems are generally more stable, approximating the natural functions of an aquatic ecosystem more comprehensively with more space natural processes to occur. When the time for maintenance does come however, a big tank is an equally big chore – sometimes requiring enormous amounts of time. Unless you happen to be in the mood to get wet, lift heavy stuff, and scrub, it can often feel like some sort of cruel punishment. 

Large overhauls and “renovations” are usually titanic undertakings so it is important to be strategic and get as many things right from the beginning as possible. It may not be practical to go back and fix mistakes later. Luckily bigger aquariums have more wiggle room and allow for larger margins of error when you are putting your aquascape together. Small imperfections or aesthetic issues disappear into the mass of the greater whole and make far less of an inpression by themselves.

When it comes time, maintenance on a very large aquarium can be logistically challenging an time consuming. Before you go too big, make sure you've considered how and who will be performing the upkeep as it will certainly be required - even if not quite as often as well smaller tanks.

Even though larger planted aquariums are more complete and can function without intervention for a long time, please don't skip water changes. Nothing is complete and nothing lasts forever, not even in nature. After a while, water chemistry will change outside of acceptable boundaries and will need to be replaced. Most natural aquatic ecosystems have an inlet and outlet that replace old water with new water - sometimes continuously. You don't have to do them very often - a partial water every month will go a long way in keeping things the way you want them and reduce the chance of laborous remedial measures being needed in the future. After all - a few buckets of prevention is easier than a metric ton of cure.

As would be expected, larger tanks are also more expensive – that might seem obvious but don't forget to account for all the things that go into the bigger tank as well. It's not just the glass box that has a bigger price tag. The beefier equipment required to power it all does as well. Aquarium plants, are expensive, as are fish and shrimp. If you’re just starting out, figure out how much effort, time, and money you are willing to invest into your planted aquarium and choose how to start accordingly. Don't get too ambitious and dive into a tank that you can literally dive into. 

Black Neon Tetras (Hyphessobrycon herbertaxelrodi) are an excellent, sometimes overlooked option for planted tanks. They remain small between 1" and 1.5" and look amazing in an environment full of lush greenery.

In reference to a densely planted freshwater aquarium with plants, fish and shrimp primarily originating from the tropics, we would classify “large” as anything exceeding 55 gallons. While that is a small tank for saltwater and a medium tank at best for a fish-centric aquarium, it is a lot of space to work with for the kind of planted aquariums that we are discussing. Many planted aquarium enthusiasts can be very detail-oriented and there are a lot of details to deal with in even a ‘modest’ 55 gallon aquarium. The visual impact of good aquascaping also visually dramatic - the tank will appear deceptively spacious and a well-thought-out selection of plants in a well-crafted layout will create a dramatic sense of depth.

The middle ground - a good compromise for beginners

If you are just starting out, a medium size tank is the most practical and advisable way to go. Of course you can go bigger or smaller if you've already made a choice based on your vision and abilities. For those that have not decided yet, we just want to point out that medium size tanks often represent a goldilocks option. They have sufficient space for an imaginative and interesting display with room for a wide variety of species without becoming overwhelmed. In the context of a tropical freshwater planted aquarium with fish and shrimp in 2024, that would be somewhere between 15 and 40 gallons, with 20 being an ideal starting point if you don't already have a plan or strong preference for something else and already know what you are doing.

A 20 gallon tank, similar in proportions to the popular US "20 gallon long” (30" x 12" x 12") standard, is well suited for creating a masterpiece of an aquascape that is interesting, coherent, and endlessly fascinating. The tank also has pleasing proportions for a planted aquarium. As much as things have changed, it has always been a highly regarded option and is an excellent canvas on which to create a detailed and complex aquascape. 20 gallons is a large enough volume of water to act as a buffer and keep changes, like temperature, slow - as they are intended to be.

A moderate sized tank of 15-25 gallons is an ideal starting point. The tank shown is has a taller aspect ratio than a 20 gallon long but is still a very good candidate.

The related 20-gallon “high” (24” x 12” x 16”) is a very good alternative and may be favored by some aquascapers for its taller, more modern aspect ratio. Floor space is a bit more limited so you may not be able to use as many species, but it can showcase larger plants that become much more impressive if allowed to grow taller. Just keep in mind that light intensity declines exponentially with distance so the taller tank will need a brighter fixture to achieve the same intensity of illumination at the substrate level. The only significantly consideration is lighting intensity, especially if you want “carpet” plants that are, by definition, short and almost invariably demand a lot of light. Taller stem plants can also drop their leaves at the bottom with insufficient light but neither of these issues is a dealbreaker since, in the grand scheme of things, fantastic results have been achieved in taller tanks. CO2 injection can mitigate these problems as well as we will discuss later.

For those with less space to work with, a 15-gallon (24” x 12” x 12”)  is also a fantastic choice. It has significantly more generous proportions than the ubiquitous 10-gallon “leader” tank (20” x 10” x12”) that so many, including myself, started our aquarium journeys with. The floor area feels significantly more generous compared to a 10-gallon, more so than the extra 5 gallons of volume might suggest. Many rimless aquariums are a similar size with 18-gallon "60p" (24" x 14" x12") tanks quickly becoming an unofficial standard. It is an aesthetically pleasing option with plenty of scope for aquascaping and should be widely available from virtually all manufacturers.

Great Things in Little Packages - the Mini, Micro, Nano, and Pico Options

Strategic layout and a selection of small plants makes this aquarium appear much larger than it is. Without the dog, you wouldn't know this tank is miniscule

The smallest planted aquariums, termed “nano” and “pico” tanks, seem to be all the rage these days. These 3-6 gallon aquariums represent a compelling challenge to achieve something extraordinary in a minuscule amount of space. Working with the most diminutive (reasonably sized) aquariums can be an extremely fun and rewarding extra-credit challenge. While not exclusively the preserve of seasoned experts, many nano aquascapers started with more conventional sizes, from which they learned the skills of the trade. Those skills are important when dealing with the unique challenges of nano aquariums with their potentially unstable nature. 

The less water a tank holds the quicker relevant parameters such as pH, oxygen and CO2 concentrations, hardness, and temperature can fluctuate for reasons that can be difficult to discern. They require more frequent attention, monitoring, and maintenance to prevent any problems from developing or progressing too fast as it is not difficult for the whole setup to suddenly crash - sometimes overnight. In the case of the smallest nano tanks, partial water changes involve little more than a red Solo cup and about 45 seconds, which is fortunate as they should be performed as often as feasible.

That being said, we recommend that absolute beginners avoid starting their first planted tank in a thimble – you are much more likely to succeed with a larger tank and there’s nothing more demoralizing than experiencing your efforts turn into green sludge multiple times. Get good first by selecting an easier, more forgiving format, and then transfer what you've learned to a nano planted-tank project that may not have as much room for error. It would be like giving up in frustration after playing a game on hard mode without allowing yourself to have a bit of fun, learn the necessary skills, and experience the triumph of success, simply by first lowering the difficulty. Without the experience of creating larger aquariums with a higher probability for success, you may find some of the challenges that crop up to be daunting. Worse yet, without the experience of having succeeded before, you’ll be much more likely to give up, and that is a shame. before you try to run.

Though undoubedly cool, tanks that are too small can be very limiting unless you know what you're doing. There are only two species of plants in here and the fish may not be long-term residents as this tank has no filter or CO2.

If you are dead set on starting small (or lack the space for anything bigger), a 5-10 gallon tank is a reasonable option. It may not be in the pico realm but it’s small enough to fit in a lot more places and can even go on a desktop. A lot of rimless tanks in this size are better proportioned for planted aquarium use and will have enough space for a compelling aquascape while being able to maintain reasonably stable parameters. While limited in your choices, a few fish are suitable for these creations or you can always have a colony of shrimp. Anything much smaller will have a hard time supporting fauna. Though fish and shrimp are sometimes an afterthought for aquascapers, they are still a vital component of our aquariums and provide an immense amount of visual interest and movement that plants alone cannot replace. The interaction of flora and fauna is one of the key joys that make planted aquariums so endlessly fascinating.

Pair of Scalet Badis (Badis Badis formerly Dario Dario)
A pair scarlet Badis - a tiny fish with fascinating behaviors from small ponds and even rice paddies in South Asia where they have adapted to slow moving, poorly oxygenated water. They make for charming inhabitants of a small aquarium but can be picky eaters.

The best thing about planted-aquariums is the amazing experience of creating one and watching it turn into something amazing. Even though there's a trend toward smaller and smaller aquariums, the easiest size for a beginner lies between 10 and 25 gallons. If possible, we highly recommend that you start there to maximize your chance for success. Don't miss out on one of the most fascinating and gratifying experiences out there!


Style and Substance: Rimmed vs Rimless Aquariums

This Old Tank

When got my first aquarium in the mid-1990s, tanks were largely limited to a progression of standard sizes with characteristic plastic rims at the top and bottom. Anything else was an expensive, potentially time-consuming proposition that involved custom glass and, ideally, liability insurance. 

A typical rimmed glass tank - the most common and popular aquarium style. The black pastic rims may be unsighltly for a planted aquarium but can also hide the waterline and allow the easy use of a cover

This tank style is still widely available today (at least in the US), and comprises the bulk of aquariums found in big-box retailers - often for very reasonable prices. While some may consider the rims frumpy, the value proposition is hard to argue with and while unphotogenic, they detract little - in real life - from the splendor of a beautifully aquascaped and thriving underwater paradise. 

Rather than considering them ugly, some find the rims reassuring. The plastic bracing continues to do its job today, reinforcing the tank structure against the immense pressure of water, keeping the glass from bowing and protecting the edges of the glass from getting accidentally chipped. They’re still as good of an option as they ever were and if you’re starting out and want to stay within a smaller budget, you’re better off spending the money on CO2 and lighting. A conventional rimmed aquarium, in and of itself, does not limit what you can do but insufficient lighting and CO2 supply do severely limit your options for plants, how fast your they grow, how robust they become, and how colorful they will be. It would be a stretch to say that an accomplished aquascaper who has only worked with rimmed tanks has “missed out” on the best parts of the hobby, while someone who has never experienced CO2 injection - something that makes a visible difference in hours - has indeed never experienced some of the best of the planted-aquarium hobby. Nearly 80% of aquarium plant species were discovered in habitats with natural CO2 concentrations that exceed 10 ppm. Very few of these can survive or grow reasonably well in the confines of an aquarium environment with CO2 concentrations regularly dipping to 0.1 ppm. Growing plants with insufficient light is similarly frustrating and in a situation where you have to choose, you would best be served with better lighting and CO2 compared to a fancier rimless tank. Your overall experience will be much more rewarding and eye-opening.    

A small but important perk of rimmed aquariums that I've rarely ever seen discussed but have certainly experienced, is that the top rim hides the waterline, creating a uniquely immersive viewing experience. I’ve never quite been completely comfortable with seeing the waterline exposed on rimless tanks, though that is likely because, for the majority of my aquarium-keeping life, seeing a waterline meant I’d been slacking on top-offs.

Rimmed tanks als have a built-in lip to accommodate a cover in case fish get any ideas about flying. If any of your tank inhabitants (or potential tank inhabitants) are prone to engage in that kind of risky behavior, you will probably want a cover to avoid finding fish jerky all over your living room floor. In that case, you may be better served by a rimmed tank of a standard size for which covers are readily available. A cover on a rimless tank can be unsightly and negate its aesthetic appeal, whereas a cover is barely visible on a rimmed aquarium. Even if you can get the fairly obscure metal clips that allow you to mount a recessed cover over the top of a rimless aquarium - the cover will still be easily visible and potentially irksome.

A rimless glass aquarium
Rimless glass tanks have become very popular, especially among the planted aquarium community

Covers aside, it's hard to argue with the aesthetic value of a rimless aquarium in the context of a hobby as aesthetically focused as freshwater aquascaping. Other than just the lack of a rim, these aquariums come in a much more diverse variety of sizes and shapes that may better suit your aquascaping needs. I like long, short aquariums and there is no shortage of choices for me today - whereas that aspect ratio used to be exceedingly uncommon and the comparatively thick black rims would have ruined it anyway. Though rimless tanks are generally more expensive for the same capacity, prices have come down dramatically over the last few years and smaller aquariums in the 5-20 gallon range are now more or less comparable with the legacy options. Unless you are considering much larger sizes (to be discussed), the economic argument for rimmed tanks is quickly becoming less and less relevant.

Takashi Amano, "Nature Aquariums", and the Rimless Revolution
An Iwagumi inspired aquascape. Popularized by legendary aquascape and artist Takashi Amno, Iwaguni uses stonework as the central theme and one or more short plants.

Many people consider the rise of the rimless glass aquarium to be a direct result of the planted aquarium revolution that started in the early 2000s following the wild popularity of aquarist and photographer Takashi Amano’s foundational work on “Nature Aquariums”. It was a massive leap for aquarium plant enthusiasts and ushered in a full paradigm shift in aquascape design. I still remember hearing my jaw drop when I first saw his work. 

Inspired by the traditional East Asian art of replicating landscapes in miniature using rocks, moss, and Bonzai - a common sight in the courtyards of aristocratic homes in Imperial China and Japan. Amano took these dramatic vistas that, often depicted mountains and valleys, and submerged them. The result was nothing short of surreal as these miniature worlds, with their supernatural, dream-like serenity, captured the imagination of anyone who saw them. It instantly turned aquarium design on its head and was the single greatest contribution to the modern concept of a planted aquarium.

Beyond simply being aquariums with plants, aquascaping and planted aquariums became a movement that exploded in popularity - along with the rimless tanks Amano favored. Other concepts from Amano's work, like the focus on depth and perspective, carpeting plants, statement hardscapes, ornamental shrimp, CO2 injection, and the Iwagumi subgenre, have become integral elements of many planted aquariums today. Even the terms "aquascaping" and "aquascaper" were a direct consequence of the art form that emerged. We were called "fishkeepers" before that - because why else would you have an aquarium?

Neocaridina davidi or Neocaridina rubra - Red Cherry shrimp in an aquarium
Cherry Red Shrimp (Neocaridina davidi, ex. herteropoda) are wildly popular in aquariums today. Though Amano mostly used the aptly named, "Amano Shrimp", colorful variations of these and related ornamental shrimp are a mainstay of planted aquariums today.

Though aquariums with plants as the main attraction was first pioneered by the Dutch in the 1930s, few contemporary aquarists were overly enthusiastic about them. The style was tired and needed new blood. Many "fishkeepers" used live plants in their aquariums for their ecological benefits for the fish, and plastic plants in neon colors were probably more widespread. Today, with the rare purist exception (usually related to organized competition), even “Dutch” inspired tanks encorporate elements of the "nature aquarium" concept such as carpet plants. Most combine elements of both styles, along with more contemporary themes that continue to evolve. Far from replacing it, Amano's Nature Aquariums revinvigorated the Dutch concept with new ideas, techniques, and standards. Today there are many more "Dutch" aquascapes than there were in 1997 because of a man with a completely different aesthetic.

Modern planted tank with Dutch and Nature Aquarium elements featuring neon tetras
Many planted aquariums today feature a combination of Dutch and Amno inspired themes.

Though aquariums featuring plants as the main attraction had been around since the 1930s, few fishkeepers were overly enthusiastic about them. The style had become dated, the equipment, including ye olde CO2 systems, were fussy and very expensive. It needed new blood. While many “fishkeepers” included live plants like Anubias, Amazon Swords, and Cryptocorynes in their tanks, they did so mainly for the benefit of the fish. Plastic plants in neon colors were probably more widespread and often shared spaces with live plants. It was all about cleaning the water and creating oxygen. The Dutch concept had become fairly obscure. Far from displacing it, Amano's Nature Aquariums reinvigorated the Dutch concept with new ideas, techniques, and enthusiasm. Today, more people know about Dutch-style tanks than when those were the only game in town. Most planted aquariums, with the rare purist exceptions (usually related to organized competition), are a combination of elements from both styles.

Technology Leads the Way

Thick panels of conventional "float glass" have a greenish tint that made rimless thaks difficult in the the advent of low-iron glass.

Once challenging to make and very expensive, advances in technology, construction techniques and, consumer preferences have made rimless aquariums much more common and much less expensive. Rimless tanks, without the plastic bracing, require stronger glass and the development of low-iron glass enabled thicker panels to be used without a slight greenish cast. Even larger tanks, requiring even thicker glass, can be constructed with excellent optical qualities. The almost exclusive use of tempered glass ensures that the panels are also stronger per pound and less prone to chipping, thus eliminating the need for edge protection and additional bracing for small and medium tanks.  

Advancements in the silicone adhesive used to cement the sides together have made joints stronger and able to hold tight without any help. New construction techniques to strengthen those joints have also borne fruit in the form of nearly seamless edges with little to no visible silicone. CAD analysis identified possible structural issues and failure points and, among other things, revealed which sizes and proportions were the strongest and most structurally sound. Many of the more modern geometries of rimless aquariums are a result of this analysis. These advancements collided with growing consumer demand and the economy of scale. Availability rose and prices fell.

As a result of their popularity, especially for aquascaping uses, many accessories produced for aquatic gardening are often available only for rimless tanks and have made this style ever more practical and desirable. Many of these products, including tool holders, lily pipe brackets, and over-the-rim CO2 drop checkers, are designed to be either minimally visible or to complement the sleek geometric lines of a rimless aquarium. If you want to use over-the-rim accessories nowadays it's rimless or bust literally - as most are glass and will shatter if you try and squeeze them over a wide plastic rim.

Accessories like this over-the-rim dropchecker (used to monitor CO2 concentration) look great on rimless tanks and reflect the widespread usage of CO2 fertilization in planted aquariums today.

Around the same time, another change was brewing that would have profound effects on the world at large and cement the rimless tank design as the preferred one for planted aquariums. The blue LED had been invented in early '90s Japan - which made it possible for LEDs to produce white light. Initially, these were not bright enough for growing any plants but technology marched on and by the 2010s, LEDs, with their efficiency and flexible spectrum became a mainstay for growing aquarium plants. Their simple electronics enabled attractive and compact form factors and today, the combination of a rimless tank and LED light is by far the most common configuration for a planted aquarium.

Rimless Tank Sizing and Shrinking Standards 

Unlike the olden days, rimless tanks do not come in standardized sizes with each manufacturer preferring different sizes and different methods of naming models. Reflecting their widespread usage as planted aquariums, many are now sized according to length not volume as length is arguably a more relevant metric for aquascapers. On one hand, the lack of standardization and the proliferation of shapes and sizes allowed for tank shapes and proportions that were better suited to plant aquaria. On the other hand, the endless array of possible shapes and sizes made accessories, particularly covers, more difficult to find. Those are usually only available through the original manufacturer or have to be custom-made

Miniature Nano Pico Rimless Glass Aquarium with Terrarium Scene
Rimless glass tanks are most frequently available in much smaller sizes than traditional rimmed tanks. This is a bit of an exaggeration but is an example of how small they can get.

Aquarists who have been in the industry for a few decades may have noticed that the standard aquarium size has been shrinking - noticeably. The reasons are multifaceted and, by and large, driven by the increasing popularity of rimless tanks and planted aquariums. Though large rimless tanks are spectacular, they are not as common, with most models ranging between 20 gallons and 5 gallons. Excepting the recently popular 5-gallon model, conventional rimmed tanks are rarely smaller than 10 gallons, which was once considered “nano” with the “standard” 55-gallon being widespread. Today, the 40-gallon “breeder” (36” x18” x 16”) is especially beloved.

Shifting consumer preferences toward more aesthetically pleasing and elaborate (but less conspicuously space-consuming) aquariums have reduced the relative demand of large aquariums which has made them harder to justify for many retailers. Compared to their rimmed counterparts which were designed first and foremost for fish, rimless tanks are overwhelmingly used for planted aquariums which are often smaller and feature smaller animals (as previously discussed). A beautifully aquascaped 24” (60cm) aquarium arguably has more to offer within its 18 gallons than a 100-gallon behemoth with goldfish and a few plastic decorations. Quality over quantity I guess.

Nested Rimless Aquariums
Rimless tanks can be shipped nested like Russian dolls so there will always be small tanks, for logistical reasons.

To maximize shipping efficiency, rimless tanks are often nested inside each other like Russian dolls and manufacturers frequently make a “series” of tanks designed for just that and distribute them in sets. A hypothetical 22-gallon tank may have similarly proportioned 12, 8, and 4-gallon siblings and many retailers will have a consistent inventory of small tanks simply because it’s practical. Far from being a burden, nano planted aquariums have gone viral and are no longer a niche product.

Without the surprisingly consequential bracing, larger rimless tanks are quite challenging to produce and transport. To support the weight of so much more water, they need to be built from significantly more expensive thicker panels of glass that are extra "iron-free" for optical clarity. In addition, without any external support, specialized construction techniques need to be used to ensure seam strength so large rimless tanks will jump in price. Despite the stronger glass and joints, they still benefit from structural reinforcement (most commonly, a technique known as "Eurobracing") to enhance their structural integrity and prevent bowing. If you have your heart set on a 100-gallon aquarium, consider the conventional rimmed version as a rimless one will be quite difficult to find, difficult to transport, and difficult on your budget. The visual impact of rims is minimal for a huge tank and it will be more than beautiful enough. Bracing large rimless tanks may dimish their clean lines somewhat, but is a very good idea for long-term safety.

Rimless Glass Tank with Eurobracing
Larger rimless glass tanks still need structural support. This is an example of "Eurobracing" which supports the tank without being too visually intrusive

Small, Smaller, Nano

Perhaps due to the availability of small rimless tanks, particularly well-suited to urban dwellers with limited space, the practice of creating nano-sized aquariums exploded in popularity. LED lighting, new miniature filters, and advancements in CO2 fertilization (such as our CO2ONE system) made these petite tanks particularly well-suited for planted aquariums which, as a genre, was already trending toward miniaturization. By the 2010s, a variety of newly discovered (or newly) popularized plants and animals of comically small proportions made the subgenre increasingly compelling and one of the most important segments of the planted aquarium hobby today. The old concept of “Bigger is Better” was out the window as the pendulum swung hard toward “How small can you go?”. Tiny is now big business. 

Few examples so vividly illustrate how wildly popular and commercially important nano aquariums have become as the story of the Celestial Pearl Danio (CPD) which is distantly related to the “micro rasboras”, themselves a loosely defined group of somewhat related species of the most diminutive proportions. They were mostly discovered in the 1990s and languished in obscurity until the late 2000s. In contrast, the CPD (Danio margaritatus), formerly known as the “Galaxy Rasbora”, was discovered by local villagers from Myanmar in August 2006 who sold them to an aquarium shop in Yangon where it caught the eye of a local fish exporter who introduced it to the wider aquarium community which wasted to time getting to work. By 2007, CPDs were being captively bred and were in aquariums across the world. I had five by 2008.

Celestial Pearl Danios (Danio margaritatus) are very small fish with brilliant colors. They are a fairly new addition (along with other very small cyprinids) discovered in 2006 and frequently grace smaller aquariums - though they can certainly take advantage of larger tanks as well.

We’ll explore the topic of nano aquariums as well as micro rasboras in another article - so stay tuned. If you’re interested in learning about some of the plants that are particularly well-suited to nano aquariums, check out our Aquarium Plant Species Guide for more information on specific plants. We used to produce many of these plants commercially in tissue culture and the Plant Guide is a relic of our old plant store - which has since been discontinued.  

Life in Plastic, is it Fantastic?

We’ve mostly been talking about glass aquariums but there are increasingly popular acrylic models that are really attractive and often lighter. They have an even “more” seamless appearance since they can be welded and bent to imaginative shapes. In my opinion, unless you get a great deal, I wouldn’t seek them out. They are still, by and large, much pricier than glass – high quality acrylic is very expensive – and more importantly, they can scratch much easier. 

Every aquarium in the world will eventually get a layer of algae – diatoms – attached to the inner surface of the tank and you’ll have to be extra gentle with acrylic tanks. It makes a normally quick (and somewhat cathartic) task into a much bigger ordeal. Never use scrapers – specifically the ones that use razor blades with these tanks – you will scratch it. 

Acrylic can also discolor with age. While the effect shouldn’t be too obvious, it’s not desirable and the warm, slightly acidic waters of your typically brightly lit freshwater planted aquarium could make it happen faster. For the larger sizes, that acrylic tanks are usually preferred for it is potentially more visible since they use much thicker panels. 

Avoid most other types of plastic tanks. They’re common with really cheap kits and while those can be fun (especially if you can hack the lighting), they’re not a great place to start out. They damage too easily. Polycarbonate aquariums may be okay, but they are very uncommon and really easy to scratch (think the outside of a well-used Nalgene bottle).


Aspects of Ratios and Proportional Representation: Aquarium Geometry
An very longer aquarium is a good place to start. Many find getting the composition right is easier in this format and you can explore various techniques and motifs to learn the skills and develop your own style.

Planted aquariums are best suited for longer lengths so that there is more space for a satisfying aquascape. Normally you'll want one that is atleast longer than it is tall. If you are just starting out, getting experience with many species and design strategies is easier in a tank with more floor space and this experience can be invaluable for your more specialized projects later on especially if you discover your own design language and preferences. That doesn’t preclude the use of tall tanks especially for taller plants and even vertical tanks that are taller than they are long can be a good choice for specific projects (shrimp tree anyone?) but they’ll usually end up being a struggle for the beginner and really limit your aquascaping.

Light Travels Fast but May not Get Far

Tall tanks have one major drawback for planted aquarium use – light is one of the many forces that follow the cryptic sounding “inverse square rule” which simply means the intensity decreases exponentially as a factor of the distance. So a light source that is twice as far from the substrate needs to be four times as bright for the same level of substrate illumination. To make matters worse, water absorbs light – starting from the red end of the spectrum. That's why there is virtually no light past a certain water depth in nature and fish residing on the ocean floor are blind or have evolved bioluminesence in the total darkness.

Undersea canyon showing how dark it gets with increasing water depth
Water absorbs a lot of light. Along with the inverse square rule, taller tanks will need brighter lighting if you want sufficent light at the substrate level.

To make matters worse, shorter plants, as a rule, tend to be the most light-hungry (since they usually evolved in shallower waters that receive more light). Carpet and foreground plants are some of the most sought after elements of modern planted aquariums, need the highest lighting intensity and grow closest to the substrate. Most light fixtures of a given size were designed for the most commonly shaped planted aquariums of that length. They may be insufficient for plants at the bottom in tanks taller than ones they were designed for. To make matters worse, a searing bright light may stress out the plants at the top just to get enough light to plants at the bottom. 

Closeup of carpet plants Hemianthus micrathemoides
Carpet plants like the ones shown here grow low to the substrate but need the most light. Taller tanks need to have much brighter lighting due to a combination of the "inverse square law" of light intensity and the absorption of light by water.

CO2 fertilization helps a lot and may eliminate the issue if the tank is not excessively tall. Increased CO2 concentrations reduce the lighting demands of some plants and prevent light stress in others. For a disproportionally tall aquarium, CO2 is mandatory.

Hexagonal aquariums used to be kind of trendy even before my time. I’m not a fan – if you have a vision, go for it. Just remember lighting and CO2.

Bowfronts are fun but…

Bowfronts magnify the scene inside the tank but can have an unpredictable effect on how your aquascape looks. They are also difficult to clean.

Bowfronts, aquariums that have one “bowed” panel along the length are kind of cool. The idea is to create the illusion of a bigger tank and can be quite mesmerizing. In general, my opinion is to pass unless you really want one. They are harder to clean and you can’t use the oh-so-satisfying razor scrapers. Diatoms are a fact of life for any aquarium and anything that makes them harder to clean is a “no” in my book. The magnification effect is greatest at the center of the aquarium which can mess up your display if you didn’t center your visual interest point – and most aquascaping orthodoxy recommends against centering. Planted aquariums are best visualized the way that they are designed - without any visual "enhancements" that can have an upredictable result on presentation. The tanks also look goofy against the straight edge of a surface so you might end up going with a stand that you otherwise don’t care for. They are more expensive as well – though I’d skip them even if they weren’t.

I’ve only seen one example of a vertical bowfront before and it has a bit of a funhouse mirror effect that you may or may not like. Again, it’s harder to clean and it distorts your aquascape in ways you may not find flattering so I would pass – but it’s entirely up to you.


A word about complete tank kits and system aquariums

Empty glass aquarium with hood and stand
Aquarium kits with a hood are, as a rule, not designed for plants. The lighting is usually much too dim. They can however, be a good deal for a tank and stand. Just be aware that you will have to get a better light.

For the beginner, what better solution is there than an all-in-one kit? Or so you would think. However, most kits range from bad to mediocre and are almost always a bad value. There is no such thing as a “planted aquarium kit” that is widely available – especially not at a big-box store. Many aquatic gardening enthusiasts might wonder why else would anyone be buying an aquarium but the truth is, despite the rising popularity of planted tanks, most people are still buying them for fish and the industry has no reason to include more specialized equipment plants need when most of their customers won’t use it. 

An aquarium kit often consists of three parts. It's not hard to put your own together that suits your needs better. Just purchase the following and your needs willl be much better met.

  • Tank

  • Filter

  • Light

Add a heater and CO2 system and you have all the major pieces of a planted tank so you can focus on what's important - the stuff inside.

The pet-store tank kits (unless you have a store that specializes in aquarium plants) are often put together at the store. The tanks are usually standard sizes paired with woefully inadequate lighting – sometimes using truly ancient technologies. You will almost certainly need to purchase a light anyways to grow any plants. It doesn’t have to be very expensive but you’ll have toss the 1990 era fluorescent, fish-only hood light. Filtration will usually be adequate as planted tanks are not as filtration-dependent. Some may even include some aquarium gravel in birthday cake colors which you probably won’t use. Others include air pumps and things attached to air pumps that not just loud but usually do more harm than good in a planted tank. 

Aquarium with matching hood containing a light
Many "system" tanks have integrated lighting that is difficult to replace if it is not sufficient - an in many cases, it will be insufficient.

Sometimes stores offer deals on aquarium kits that include a stand. As long as you are aware that you will need to replace the light, go ahead and grab it. Just don't expect to be able to use the included lighting for anything other than to illuminate fish in a dark room.

There are also more premium tank “systems” from fairly reputable companies that usually include a filter and lights integrated into the design. More often than not, they are truly all-in-one with the filtration built into the tank itself and the lighting built into the hood. They are usually not a standard size. While they can be a convenient all-in-one option, we tend to recommend against them since they’re sold at a significant markup and it’s difficult to change out the proprietary equipment if they break or do not suit your needs. The lighting in a lot of these in particular is mediocre – though the better ones usually work adequately when combined with CO2 injection, it’s still a compromise that you also pay more for. Not being easily able to replace the integrated lighting is a significant issue that could make your expensive purchase basically useless for plants.

Complete CO2 system from ABC Plants
A good CO2 system (such as CO2ONE by ABC Plants) is the single best investment for a planted aquarium. The price difference between putting together your own (superior) tank, light, and filter is usually more than enough to cover CO2 - which completely changes the game!

I would still, as a general rule, recommend that put your own system together. You won’t have to scrap the whole aquarium (and all the stuff in it) if you outgrow the filtration or lighting or something breaks. A comparable rimless aquarium paired with a filter and light specifically designed for aquarium plants along with a high-quality pressurized CO2 system (such as our CO2ONE), will usually cost less and, more importantly, offer a significantly better experience than almost any of the all-in-ones. Don’t let the box containing your precious underwater slice of Eden hold you back!

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