Aquascaping a 20-gallon long tank probably presents the most rewarding of challenges to both the noob and the experienced hobbyist alike. Common dimensions for this tank include 30 inches in length, 12 inches wide, and only 12 inches in height. The dimensions of this tank allow a great range of possibility in design. The stretched shape opens up new scapes that might not work out well in a more regular or taller tank. It also brings along its own share of difficulties that are to be effectively handled with a careful plan and by keeping in mind things like balance, flow, and aesthetics.
Everything from my earliest tank experiences onward has been varied, but I continue to go back to the 20-gallon long due to its versatility. It’s a manageable size that allows me easily to explore different ideas where space is still ample, yet small enough not to maintain without having to invest huge time.
I am going to take you through the step-by-step process of setting up a beautiful 20-gallon long aquascape, from concept to its execution, in this article. In the course of it, I will also be sharing my experiences, valuable tips, and things I have learned along the way.
Understand the Tank Dimensions and Scape Goals
One of the key things to consider when designing a 20-gallon long aquascape is how you can play the dimensions of the tank to your advantage. You could create an extended landscape-simulating riverbanks, mountainous valleys, or open plains-with its elongated horizontal layout and take advantage of having it long and shallow, focusing less on vertical height.
Choosing a Theme
Before even touching the substrate, I am always thinking about the overall theme or storyline of the tank. Am I emulating a natural riverbed, a lush jungle, or maybe a minimalist Iwagumi stone scape? Over the years, what has worked for me-which in turn starts to eliminate the tendency to throw everything in-is sticking to some sort of overall idea or theme.
For one of my favorite 20-gallon long tanks, I wanted to create a quiet, Japanese-inspired Iwagumi setup centered on the balance of rocks and a few carefully selected plant species. What attracted me most to this style is because of the calmness it portrays: simple, elegant, and a form in which every rock has its place, and plants serve to complement rather than outshine the hard-scaping. On the other side of the coin, I have also kept high-tech, plush tanks with a wide variety of plants including carpeting plants, stem plants, and mid-ground species. These tanks are entertaining to maintain but require more equipment and labor, especially regarding things like lighting and CO2 injection.
It’s done and dusted-it can certainly be done, either high-tech or low-tech with a 20-gallon long, contingent very much upon vision and what kind of maintenance the keeper is willing or able to perform.
Finding the Right Hardscape Materials
Once I have chosen the theme, I start looking for just the right kind of hardscape material. This is my fun part of the process: carefully choosing rocks for an Iwagumi layout or searching out twisted-gnarled pieces of driftwood for a natural biotope, the hardscape is the backbone of your aquascape. It dictates the overall flow and composition, so it is worth taking the time to get it just right.
For my Iwagumi scape, I must have spent months searching for the perfect set of Seiryu stones. These are rocks exhibiting a rough texture and bluish-gray color that conjures up a nice contrast against a backdrop of vibrant green plants. I do recall finding this really large, flat Seiryu stone that would be the centerpiece for my tank.
It had just the right mixture of cracks and crevices to give it character without overwhelming the rest of the layout. It’s this sort of subtle attention to detail that really makes or breaks an aquascape.
Speaking of a scape with driftwood, I have spent hours in the local aquascaping shops, flipping through piles of driftwood trying to find that perfect piece.
There’s just such beauty in the driftwood-no two pieces are ever the same, you cannot force it into a layout, and it works or it does not. I’ve learned this piece of wisdom the hard way, having spent so much time through the years moving pieces around only, of course, to end up going back to the original setup. Patience, I have learned, is the most important virtue when building a hardscaping.
Substrate Choices and Plant Selection
Once the hardscape is in place, one would need to choose the right substrate and plants. For a 20-gallon long tank, substrate fulfills two functions: the function of aesthetics and functionality. You want something that looks like it belongs there and will lead to healthy plant growth. I always recommend a nutrient-rich substrate if you plan on having rooted plants since this helps them establish healthy root systems and thrive over time.
Substrate Layering
In my 20-gallon Iwagumi tank, I used a two-layered substrate system. First, the bottom is made of soil with a lot of nutrients in it that will gradually provide the nutrients to the plants. On top of that, I placed a very thin layer of fine gravel for beauty. It shall ensure that the planted ones will get enough nutrients, yet still show clean and minimum appearance.
This will also create a nice contrast with the pale-colored stones of Seiryu, making this aquascape pop visually.
In tanks where I have done a more jungle-like design, I have layered a heavier substrate with larger grains toward the back of the tank, gradually tapering that off toward the front with finer sand. This gives the illusion of depth and can even make a tank seem larger than it is. Playing with substrate heights and textures is, for me, one of the easiest ways to add dimension onto a shallow tank, like a 20-gallon long.
Choosing the Right Plants
The selection of plants is where your personal preferences come into view. I am a staunch believer in using plants that suit the scale of the tank and the overall design in mind. For a 20-gallon long, it is best to avoid using plants that grow too tall or grow very fast since such plants tend to overpower any layout quickly, making maintenance a nightmare.
For my Iwagumi setup, I had chosen a simple plant palette: Eleocharis acicularis or dwarf hairgrass for the foreground and a few scattered patches of Hemianthus callitrichoides, commonly referred to as HC Cuba, to make a fine carpet. The dwarf hairgrass will add a soft, grassy texture that is in comfortable contrast to the rugged stones. The HC Cuba adds a soft, low-growing ground cover which should help to tie the whole scape together.
I feel that an Iwagumi scape should always keep the plant palette to a minimum-so as not to distract from the hard-scape, the real star of the show.
I just love playing with varied species that layer and contrast in more lush, high-tech tanks. Some of my favorite plants to include as a mid-ground are Cryptocoryne wendtii.
It’s so hardy, adaptable to a variety of lighting conditions, and with those beautiful, broad leaves, it brings such a rich texture to any aquascape. Another favorite of mine would include Rotala rotundifolia for the background; it grows out quickly and provides a burst of reddish-pink, just making a striking focal point without being too overwhelming.
Balancing the Growth and Maintenance of the Plants
One of the things that I learned over time is to balance plant growth with maintenance. It is very tempting when setting up, for example, a 20-gallon long tank, to fill it with fast-growing stem plants or carpeting plants that cover every inch of substrate. For sure, in literally a month, you’ll get an overgrown situation and a bigger need for frequent trimming. My experience has been that it is best to choose a few slow-growing species which, over time, maintain their shape and form with less upkeep. For instance, the dwarf hairgrass in my Iwagumi scape took about a few weeks to finally carpet the tank and then afterward grew in a manner that required only very occasional trims to stop it from creeping too far up the stones.
In comparison, my high-tech, jungle-style tanks are often at a pace where I have to trim and replant every week, especially around areas with stem plants like Rotala or Ludwigia.
The trick I’ve learned is that, when it comes to trimming, one rotates the sessions. Instead of having to work on the whole tank at once, I take a little section every week. That way, it never looks too bare or too overgrown at any particular time, and the workload becomes really doable. The plants are also given some time to recover and grow without heavy stress.
Section 3: Lighting, Filtration, and CO2 Injection Once substrate and plants are in place, it is time to turn to some technology for the aquascape. Success in a 20-gallon long tank is going to be dependent upon finding the right balance between light, filtration, and if you are going high-tech, CO2 injection.
Lighting Considerations
Lighting is perhaps one of the most precarious properties in any aquascaping, and that is no different in the case of a 20-gallon long tank.
You don’t need super powerful lighting because of how shallow it is, but selection should be based on even coverage across the length of the tank. Most of the models I have used were LED lighting, which I find perfect for these tanks, since it gives you bright, energy-efficient light that you can adjust to suit different plant types.
For my Iwagumi setup, I used a Finnex Planted+ LED light with full-spectrum lighting that encourages health in the plants without being too much for the tank itself. The adjustable brightness settings also allowed me to tune down or dusk up depending on the needs of my plants so that they would get only just enough light without causing algae blooms.
One mistake I made early on in my aquascaping journey was using too much light. I had thought that the more light, the faster the plants would grow and the healthier the tank would be in general. However, I quickly found out that too much light-especially in a smaller tank like a 20-gallon long-can promote algae issues and growth that is not balanced. Nowadays, I believe in doing less-smaller intensity to begin with and building up according to the plants’ responses.
Filtration and Flow
Yet another important thing in preparing a perfect aquascape, filtration comes into play. I have found that for a 20-gallon-long tank, a good-quality hang-on-back filter or a small canister filter works very well. The point is to get a filter that can provide enough flow to keep the water moving and oxygenated without disturbing the layout.
A Fluval 207 canister filter provided great filtration alone with the ability for adjusted flow control in my Iwagumi tank. This gentle current worked to distribute any nutrients and CO2 well throughout the tank, making certain that all areas were appropriately ‘served’ without interfering with the sensitive composition of the plants and hardscape. One thing you need to be aware of in a 20-gallon long tank is the dead spots-meaning the areas that have very minimal water flow and where debris tends to accumulate. These places may cause algae growth and other problems if action is not taken. For this, I always position my outflow close to the middle of the tank and then use a spray bar or lily pipe to diffuse the flow uniformly along the entire length of the tank.
In other cases, I have tagged a small circulation pump on such tanks to augment the flow in weakened current multiple points. CO2 Injection: To Inject or Not to Inject? Whether to use CO2 injection in a 20-gallon long tank depends on the type of plants you want to grow and the level of maintenance you are willing to commit to. In a high-tech setup with fast-growing plants, CO2 injection is almost a must. Besides promoting faster growth, it enhances coloration in plants such that algae have a lesser chance of competing for nutrients by outcompeting them. In other high-tech tanks, I have employed a pressurized CO2 system with a diffuser to maintain consistent levels throughout the day.
This will enable the more typical stem plants, such as Rotala or Ludwigia, to reach their full potential. Of course, in my Iwagumi setup, I didn’t opt for any CO2 injection and instead maintained the low-tech aspect. Since the plants chosen herein are relatively low-demand ones, such as dwarf hairgrass and HC Cuba, they should do well without additional CO2 once they are getting enough light and nutrients. With that said, if you are really new to aquascaping and can hardly stand the thought of too much work, then I would surely suggest starting with a low-tech setup devoid of CO2 injection.
Easier to maintain, it still allows you to create a nice-looking, thriving aquascape. On the other hand, if you are up for the challenge and looking for faster growth with more vibrant colors, CO2 injection will really take your aquascape to the next level for sure. Conclusion: Patience, Passion and Attention to Detail Aquascaping a 20-gallon long tank is extremely rewarding but requires patience, attention to detail, and a willingness to experiment. Every decision, from the selection of the right hardscape material to the perfect balance of plants, lighting, and filtration, counts in the end result. One thing I’ve learned to love over time is the fact that there’s no such thing as a ‘finished’ aquascape.
The beauty of this hobby lies in that it is a dynamic process; plants grow, hardscapes shift and even your own vision for the tank may shift over time. Many times, I tend to make slight adjustments as much as a number of months afterward or reposition plants. If there is a single advice I’d give out to someone starting their 20-gallon long aquascape, it’s this: enjoy the process. You will read or get suggestions on how to fill a tank in super-quick time or get that “perfect” look in no time. Let the scape grow and develop naturally; relish the journey as much as the result.
Believe it, it is really worth it.
