Between A Rock and a Hard Place – How to Hardscape you Aquarium

When we think of aquascaping, we inevitably think of planted aquariums. But what do we do when we do not have the proverbial green thumb, or have digging fish, or cannot afford the amount of plants it takes to really aquascape a beautiful planted tank?

No fear — we hardscape!

Of course, since hardscaping forms the ‘bones’ of almost every successful  aquascape, it is perhaps the most vital piece of information any aspiring aquascaper can possess. Hardscaping is what puts the mood and structure in place upon which we create perfect, nature mimicking habitats for our fish. Get the hardscape right, and the rest of the scape will fall into place easily and effectively.

But in this case, I want to concentrate on hardscapes in the true sense of the word — the kind of scaping that really leaves you, as the title implies, between a rock and a hard place — and then elicits sighs of admiration from your friends and fellow fish-keeping buddies!

Rocks can be beautiful!

Japanese in particular take hours, weeks, sometimes months and years to find that one special rock that will bring the effect of a meditative ‘mountain’ into their gardens.  Yet others collect beautiful rocks that suggest mountains, lakes, waterfalls and other natural scenes, or that are simply aesthetically pleasing in shape and texture. They place these stones, called ‘suiseki’, on display trays filled with either a substrate, or water, because in a sense these rocks represent the majesty and beauty of mountains on a small scale in limited spaces. Collected in the wild, on mountains and in streambeds, and then displayed in their natural state, these stones are objects of great value and beauty. They are also sophisticated tools for inner reflection that stir in all who see them an appreciation for the awesome power of the universe. A single suiseki, it is said, has the capacity to present the eyes of the man all of the earth and cosmos.

Yes it is a mind-set! But it is a mindset that we can learn a lot from!

We can all learn to stop the rat race and take some time out to contemplate on the beauty with which nature surrounds us… and which we all too often pass by with little more than just a superficial glance. It is really a hankering in our souls! But we can also bring that beauty of nature inside our homes and lives by learning how to hardscape our aquariums.


There is another natural aid to help us. It is called the the rule of thirds. The rule of thirds is a derivative of the Golden Ratio, which was discovered and first realised by the ancient Greeks and has been used in all art forms for thousands of years. Not only is it said that this ‘golden’ ratio permeates all of organic life, but it is a foolproof method we can use to design and arrange elements into an order that is aesthetically pleasing, be it knick-knacks on a coffee table, books in a shelf or rocks in an aquarium. The Golden Ratio is, however, more complex to calculate and therefore is not really suitable for our specific purposes. So we will use the much easier to understand “rule of thirds”.

The rule of thirds gives us the guidelines on how to place elements within a design as a way to control where a viewers eyes will travel and what they will see. The rule states that an image should be imagined as divided into nine equal parts by two equally-spaced horizontal lines and two equally-spaced vertical lines, and that important compositional elements should be placed along these lines or their intersections.

The idea is that by placing and arranging elements with the rule of thirds in mind we create a more interesting design that results in the viewer’s eyes flowing through the intersections of the grid in a way we determined. The rule of thirds is thus a method by which to create a design that has direction, energy, tension…and ultimately, an inherent beauty.

When you’re planning out an aquascape, one of the most important aspects is to determine how and where it should draw the viewer’s gaze. In fact, whether we admit it or not, the viewer’s gaze is what the aquascape is all about! The primary goal of an aquascape is to be pleasing, relaxing, and interesting to look at for the viewer — be that viewer you, your family, or your guests. To do so, you need to set a sort of “anchor” for the mind. That anchor is called ‘the focal point’. It is the point that draws the gaze of the viewer first, and from where they can then explore the rest of the tank. We use the rule of thirds to establish where to place the focal point and all secondary points of interest.

Here’s how it works:

Imagine that there are four lines — two horizontal and two vertical — running through a square of white paper, splitting it into nine equal sections. Wherever the lines cross, is considered a a golden focus point, or ‘sweet spot’ for whatever you want to arrange on it. Let’s use a portrait to demonstrate this.

The rule of thirds is widely encountered among the best works of famous artists and photographers. In fact, several books and articles have been written on this technique. But how do we translate this for the purpose of decorating our aquariums?

This is how:

Imagine again that there are four lines — two horizontal and two vertical — running through the front of your tank, splitting it into nine equal sections. Wherever the lines cross we find the ‘sweet spots’ providing us with a possibility we can consider for placing prominent features like main stones or wood shapes in our aquascape.

Once the diagram makes sense to you, it becomes easier to understand that just as we used the same process across the top of our tank to indicate how we should use the floor space of our tank in our layout, we  can now also translate the idea further. We can plan how to adjust the various heights of our main and secondary features and perhaps even add a a third accent feature  - while keeping them all complimentary and harmonious in style. We can also take this even further into our over-all plan and choose, for example, to fill about 1/3 of our tank space with our main features, while leaving 2/3 of our space as ‘negative’ or swimming space, or vice versa. There are almost an infinite number of combinations to play with, and all can help you achieve stunning results.

And once we understand concept, it becomes much easier to see how the rule of thirds has been used in the following aquariums.

Of course, as you know, rules are made to be broken… well, sort of. Whilst it may be advisable for beginners to stick more stoically to the rules of composition, a focal point that breaks the rules will demand attention in the most commanding manner by bringing tension and interest to the scape, resulting in a truly breathtaking effect. So, there is nothing to stop you from placing your main feature slap dash in the centre of your tank, because ultimately, the final form of your aquascape  depends solely on your perceptions and taste, just as it depends on the shape and size of your specific tank.

 Images like these following below, show just how successfully the rules can be broken! Even so, there is still a suggestion of the rule of thirds in the first image, evident in the placement of the smaller stones.

If you thought you were done with learning, think again! For the correct placement of our main elements is not enough to give us a successful aquascape!

We also need to create perspective

Creating perspective, or a feeling of depth, can be one of the greatest challenges in an aquarium as they usually do not have enough depth from front to back to give a true sense of perspective. However, we can achieve the illusion of depth, or perspective by how we position the elements of our hardscape — again using the  Golden Ratio, looking down onto our layout from the top of the tank, as we have demonstrated in the diagram above.

The problem:

The most common mistake aquarists make when positioning hardscape elements, is to place their stones or wood in a very unnatural, straight line from left to right. This results in a flat, two-dimensional image.

The solution:

To avoid this, look at the diagram again, as if looking down into your tank. You can see where the suggested ‘sweet spots’ are. But now also imagine your layout as a whole consisting of several images, or screens, layered one after the other from the front to the back of the tank, each with a small gap in between, so that each image is slightly further away from the first — so that wherever you place hardscape elements, they span a variety of points in the depth of your tank. (Think of a sandwich upright on its edge with multiple layers of fillings, one after the other)

While some pieces of hardscape can share the same ‘screen’ (or point of depth), the key is to create more points by beginning at the front of the tank, where they should be lowest, in the next layer growing higher and higher, until you reach the back of the tank, where they will finally be the highest. Like The Golden Ratio, this is only a guide to creating a good sense of perspective within the aquarium.


A good example of rocks placed in ‘layers’ from front to back, as well as from side to side. Not a single rock is in the same plane as another. This creates a a natural feeling rock structure with an good illusion of depth. Also note how the rule of thirds helps creating the balance in this tank

It also helps to keep your foreground fairly shallow. Look at the images on this page and see just how narrow the foreground spaces are! An experienced aquascaper uses the space outside the front of his or her tank for ‘airiness’. Having a huge foreground compresses the midground and background, and takes away space from transitioning between them. Finally, when you position your hardscape make sure that there are clear lines for the eye to follow from front to back, paying attention to ensuring that the foreground naturally transitions to the mid-ground, and then from there to the background.

While both images below are of planted tanks, you can clearly see how the hardscaping elements  follow this particular idea.

The more experienced you become, the more your artistic eye will learn to manipulate the rules, and the more you can use, or break the rules to create a truly beautiful, individual scape. Of course, it would be sensible to gain most of that experience before you place even one single stone or piece of wood in your tank! We will talk about that a little later.

We are well on our way to designing our hardscape. But what are our main and secondary elements? What materials have we collected to create our scape, and what substrate are we going to use?

Let us begin with the focal point. The function of the focal point is to draw attention. You have to make it stand out in some way. There are a few simple things to remember about a focal point. The most important is that you should always have some sort of focal point in every aquascape. Not having any does the same as having too many: the viewer’s eyes are left wandering back and forth, stressed and uncomfortable.

Also, there should only be one real main focal point. Having more than one equally sized focal point leaves the viewer’s  mind uncomfortable and stressed, looking back and forth from focal point to focal point. So if you decide to create two or three groupings in a smaller tank, each with a focal point, make sure that one of them is taller and serves as the main focal point, while the others should be subordinate to it. 

Your approach will of course change when you scape an extremely large tank, because now you may have to create several ‘groupings’, each of which is really an aquascape in its own right, sporting its own focal point. Nevertheless, once  put together in your large tank, your series of smaller aquascapes will become a ‘whole – which means that the focal points of the groupings should not be equally sized in height or in bulk. At least one of those groupings must play the main role and should be the tallest! Secondary groups may need bulk rather than height to make them  sufficiently important.

Always keep your plan in mind while you consider the next points, because ultimately you will begin by choosing your materials based on the focal point/s you want to create for your specific tank.


Our goal should always be to interpret a natural environment — hopefully one that has been fashioned by the forces of nature’s erosion, and as little as possible by the hand of man.  Style is a very personal thing. There are really no rules, but for me the exposed ‘grain’ and ‘texture’ of a water worn river’s edge has a much richer tale to tell than the random coalescing of materials like rocks and driftwood which usually originate from mid-river, and which most aquarists so frequently choose as their starting point.

But when all is said and done, it is really your affinity for certain parts of nature, and your ability to see that which others cannot,  which will make you stand out from the crowd.

So, how about taking a walk through nature? There is much to be gained by going to mountainous areas, or river beds and sunburnt veldt to see what is there for oneself. We live in a country with a great variety of landscape forms and geology to inspire the aquarist. We are blessed with beautiful sedimentary landscapes and countless formations which visibly bear entire histories in their natural profiles. We have monkey-rocks, river rocks, striped rock, sandstone, slate and  granite-like rocks, and many more. And each of these has the most wonderful enhancing effects by way of their striations and colour, or weathering and erosion to add to their beauty and become an inspiration to any aquascaping enthusiast. So why buy materials if you can find them yourself?

And while you are out there in nature, keep a look out for materials that could possibly be used as your substrate, or perhaps in combination with a bought substrate. But also notice how these materials occur in nature. The significance of this becomes apparent when the gravel and sands are finally graded and placed in the aquarium — hopefully in the same way as can be found in rivers and streams where there are rock outcroppings and some current in the flow of the water. Check the sizes of these gravels and pebbles and where they have settled and later copy this in your aquarium. If possible, rocks, stones, pebbles and sand of the same colour and type should be used when you build your aquascape. This one-ness of parent rock, stones, gravels and sands becomes a beautiful harmonising component in the outcome of the ultimate design.

In nature finer, lighter materials are carried further before settling out and in stronger currents they literally sandblast the bigger rocks and boulders until they are smooth and streamlined.

Before you venture on your rock collecting journey, let us dwell for a moment on what to keep in mind as you hunt.

While they may not necessarily be part of your main focal point, rocks that have one corner with an acute angle (sharper than a right angle) can be set so as to present a vertical front surface, combined with a top face that slopes back into the gravel bank behind. See the rocks illustrated below and get my drift by thinking of the figure 7 tipped onto its side. If you are going to build up substrate levels, this combination of faces keeps the gravel retained behind the rock face from slowly eroding out of your higher terraces.

The best advice I can give you for collecting hardscape materials is the following:

•Never mix your rocks, or your wood! Find one kind that inspires you, and collect only that kind — but in a plethora of sizes and shapes. Judge likely rocks on the palm of your hand. The wider the base is, in proportion to its height, the more stable the rock will seem.With rocks, look for beautiful shapes and strata, with wood for gorgeous twists and twirls, gnarls and holes. Have you found one that can serve as your focal point? Remember to collect pieces that can help you conceal tank gear and filter uptake pipes. Any flat rocks with good grain can be gently leaned against the rear of the tank, providing a good backdrop and keeping the overall weight of your hardscape down. They can also be used as caves for more timid species of fish. Keep the same in mind for wood. In fact, rock at the base of wood pieces can make a wonderful combination, so keep an eye out for rocks that will work with your driftwood.

 • Think creatively, as well as practically. If you find the perfect rock for your main focal point, but you suspect that it may lack the height you need, try to find a flat, level piece that will give it the necessary elevation if it were the base of your rock. Once building you could glue your main piece on top of this base, and hide the ‘seam’ under the substrate.

•Collect a lot more than you think you will need! Think volume, rather than just height and width. A hardscape can absorb a surprisingly large amount of rock or wood, and you may have to glue together several choice pieces  to make just one main element. Smaller pieces are often nice, dotted around the aquarium floor. Yet other small pieces can serve as wedges and levelling agents in your structure. It would be silly to have to go back and get more rock or wood midway through building your scape. And you can always flog the surplus to another aquascaper!

• Before you begin, check both the strength and the stability of your tank stand, as well as the floor of the place where it is going to stand. Water is heavy and you are about to add rocks and substrate. Make sure the tank, stand or floor will not collapse under the load. Get some small Styrofoam sheets around 3cm thick, or alternatively a sheet of light-diffusing ‘egg-crate’. You will use these to put a cushion between the glass floor of your aquarium and the largest and heaviest rocks. (Your substrate will hide these)

•This is also the time to clean and sterilize your tank and install and test your tank ware. You will do this in your bare aquarium, before you begin aquascaping. If you need to test your set-up with water, remember to remove all water once you know things work. Since the tank ware are now clearly visible, it allows you to better plan how to hide these.

•If driftwood is your medium, clean, boil and soak your wood ahead of time. You will find all the information necessary on the driftwood page under our aquascaping drop-down menu. Also get fishing line or an appropriate binding wire ready, so that you can combine pieces into one, if needed.

• Have small pieces of thin flat slate ready, or cut plastic or acrylic squares and rectangles. You will not use these straight away, but you will use them to help you shore up, if you want different levels, and prevent substrate from slipping down once you work in your aquarium for real. The idea is demonstrated in the image below.

If you have brought everything you need together, let us begin! As I have said before, you are going to gain experience before you place even one single stone or piece of wood in your tank! I meant that! My goal is to teach you how pros do it. Ignore this advice, and you may well come to rue it bitterly.


So here is the pro trick:

Compose your aquascape outside your tank. Set up a workspace on a table or a bench, as it is better from a visualisation point of view than working on the floor. (Remember to protect the surface of your table against falling rocks or scraping wood) Cut a piece of flat sheet Styrofoam or cardboard into the correct shape and size to represent the floor of your tank. An old towel folded in the correct dimensions will work too. If you are not good at visualising space, cut out a back wall too — keeping to the exact dimensions as your tank.

Inspect your rock, or wood — look for big or biggest, then for medium and finally for small sizes. This makes three heaps.

Do the rule of thirds on the ‘mimic floor’ of your tank — since it is Styrofoam or cardboard, you can mark it to keep track.

Choose the sweet spot you prefer and place what you think is going to be your biggest and highest element.  Is it big enough in circumference, and tall enough in height? (Remember, you want to use the entire height of your aquarium!) If not, how can you increase the size or height (without necessarily increasing the weight)? If you are scaping for cichlids, do not even begin to consider creating height with substrate, as they will dig it out.  Are there other pieces you can combine with your main feature? Do you have to glue them, or are you just going to place them loosely next to the main one? Before you do anything drastic, find the secondary element. Place it. Does its size and angle harmonise with the big element?

Let us pause here for a moment and talk about something called the ‘strata line’ and the ‘bedding plane’. When using rock, slate or other sedimentary material, the strata line is probably the single most important design element in achieving a natural look with a sense of scale. Continuity and consistency of strata are vital, or rockwork can resemble little more than a pile of rubble. So, when setting your rocks, remember to keep your bedding planes close to horizontal. Bedding planes are the visible strata of sediment that were laid down one after the other to form the rock. Bedding planes were perfectly horizontal when they were deposited and they usually remain horizontal, unless geological stresses have tipped them into a geologist’s “syncline.”

Horizontal bedding always looks more inert and more stable. However, if you are tilting your rocks, choose a nice jaunty angle and then stick with it: keep the angle of your slant consistent all through the scape. Do not tip rocks on end, it is unnatural and invariably will look like artificial “rockwork” — and even worse when a flat rock is laid across them to form “cave.”(If you happen to be building a hardscape for cichlids, read my article, “Let’s Rock Your World — How to build a Cichlid Habitat”)


Horizontally bedded rocks always look more inert and stable



If you tilt your rocks, keep the tilt more or less consistent, but do not make your arrangement static. The complimentary ‘resting’ rock under the main feature rock in this tank is more horizontal, but nevertheless tilted in the opposite direction and yet looks completely harmonious in the whole



You could of course break the rules – or follow Japanese rules. Here we see the rocks ‘bowing’ at one another. Beautiful!

If and when I tilt rocks, I personally like to use 40° or less from the horizontal, and continue the same angle in the positioning of all my other rocks and stones, more or less right across the aquarium, trying to imitate the idea of a mild geological upheaval in times long gone by. This automatically creates a sense of scale, and will display an underlying geology that quite correctly should dwarf the size of fish (and even plants) as it would in nature. ‘Scale’ in aquarium design, as the word suggests, is all about relativity.

Very large tanks require very bold statements with very large rocks and/or driftwood. This brings all the attendant problems of weight on glass tank floors, as well as stands, home floors and floor joists. If loading is an issue, smaller rocks can be used to great effect if strong strata lines are ‘coaxed’ into the arrangement. Think dry stoned walling, only a bit looser and less rigid. Once you get going on the actual aquascape you should use a variety of sizes where possible, from large rocks to fine sands and everything in-between, to create your focal points and their complimentaries.

The image below, although again a planted tank, shows just how powerful strata lines can be. Done in a nano-aquarium of just 25 litres, one can certainly not deny that this scape is majestic!

And just to prove that it can be done without plants, and be beautiful,  here is a perfect demonstration of how powerful the strata lines and tilting angles can be — in one of the stunning hardscapes of Aquarium Design Group.

In a way, all of this harmonizing effect translates equally to driftwood as the image below proves. This spare, modern design also stems from Aquarium Design Group. The difference is that with driftwood you are looking for harmonious lines and shapes. You ask different questions, such as: Are you going to use your driftwood to simulate roots, or are they going to mimic trunks and branches? Or will they simply seem to be fallen trees,  which over time have become a tiny eco-system?


But back to work! This is the time to do what needs to be done. Create a trial scape that pleases your eye. Get the glue you forgot to buy and complete the puttying, or sticking together, before you go ‘live’.  Build and take apart.

If something bothers you about your scene, remember, sometimes, it’s as much about what you leave out as what you put in. For example, if you want to have a large rock, or a series of rocks, to represent a mountain range, the impact will be the greatest if you have some empty space around the rock/s. This contrast is what draws the eye to the mountain. Similarly, open pathways where the foreground extends back into the mid-ground or background will help create a sense of depth, while simultaneously highlighting the rocks/wood/plants along those pathways. Basically, don’t try to fill every inch of space in your aquascape with something — leave some parts open. Do however ensure that you use your entire aquarium, especially from bottom to top. Halfway scaped aquariums always have a stingy feel about them. Occasionally walk away from what you think is the final design and return with fresh eyes. Go have a drink or watch a game! Be patient during this process. Chop and change now. Believe me, it is infinitely easier and much less frustrating to make changes outside of the tank, rather than inside a water-filled aquarium!

While you’re setting your rocks, from time to time hold a light overhead, so that you can see whether you need to adjust the light-and-shade effect the rock is going to have – this is especially important if you create overhangs. When it’s all to your liking and structurally sound, give any dabs of silicon, epoxy or cement forty-eight hours to cure. With silicon there should be no lingering vinegary acetic acid smell.

Lastly, when you are sure you are finally done, consider the scene you put together once more, and this time weigh it, by thinking in terms of order and chaos.We know that nature is chaotic and perfectly imperfect. Keep this in mind when you look at your design. Avoid the temptation to over-elaborate, or to be over-orderly. Be open to nature’s surprises. Although in nature the debris of erosion settles into natural rhythms and patterns, there is always somehow a random element. Copy this. The trick is to strike a balance between order and chaos. Play with the idea that you can mimic nature’s way by how you compose your materials, from the strong linear diagonal strata to the random placing of pebbles and small stones. This is what makes the difference between an ordinary tank and an expertly scaped aquarium.

And then, at long last, once your trial hardscape truly pleases you, you are really ready to decorate your aquarium. Do NOT begin with substrate! There is a reason for this. Instead, methodically place your arrangements in your tank, one by one. After all, you cannot make any mistakes because you already made all the design decisions and you know that it will work. Remember to place Styrofoam, or egg-crate pieces (normally used as light diffusers), cut to shape, below all big and heavy rocks. It is not necessarily the weight of the stones that will crack your glass, but the weight of the stone concentrated on a few grains of sand. Also, rocks placed on substrate will invariably subside over time. And then there are the problems one can have with tank inhabitants! It is amazing what determined digging fish can accomplish in undermining rocks that rest on gravel, by moving just one grain of gravel at a time! Add your substrate last! Use a clean paintbrush to flick substrate in below rock edges. If this does not do the trick, you may have to flush it in with a little water, which means you might have to siphon that water out again before your final fill, as it will probably be dirty. Then strew your pebbles and small debris in a way that looks natural.


Finally, fill your aquarium, remembering to do so by very slowly flowing water into a small plastic, or glass bowl or plate placed securely on the substrate floor, so that you do not disturb anything with a sudden strong water flush. Halfway through it should be safe to remove the bowl. Nevertheless, it is always wiser to be patient and top up slowly, while diffusing the water pressure against a tank wall. Finally, switch on your power, filters and lights and sit back and enjoy. Whilst you should now cycle your aquarium, at least until the water is clear and in balance, you won’t have a ‘dead’ tank. You will have a tank brimful of beauty to look at while you plan which inhabitants to introduce!

Above all, have fun!

PS. Of course I have not forgotten those of you who already have a set-up aquarium. If you want to re-scape, using the ideas in this article, you can still use the same method. However, I always feel that when doing a major re-scape, it is better to temporarily re-home your fish in a borrowed tank, using their own water, as you will have to siphon this out anyway, and setting them up with their own filters etc. In this way you do not lose your beneficial bacteria, as you will just transfer a big part of the water and all your filters and filter mediums back into your re-decorated tank.

If you are nor willing to do this, I am afraid that you will have to live with the many drips and splashes aquascaping in a filled tank brings with it. Nevertheless, you can make the process much less stressful for your fish, by preparing your scape in advance, before you actually change your tank. And here’s a little tip to help you visualise better: Tape string on your tank to mimic the lines of the rule of thirds grid! A little piece of masking tape over either end of the string helps you do the job in no time at all.

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