Get to grips with hardscape


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Considering it’s the most obvious furniture in our aquaria, you’d have thought more people would pay attention to décor. Riverwood Aquatics owner Peter Cookson offers some tips.


Hardscape is the foundation to a beautiful aquarium, and can range from a stunning diorama of a weathered mountain range, complete with trees, valleys and pathways, to a basic, three-stone Iwagumi layout. 

Bearing in mind a few easy design techniques and simple placement ‘rules’ anyone can put together a strong hardscape, and thus lay the foundation for a stunning aquarium

Manzanita wood is highly textured.

What is hardscape?

Hardscape is effectively the non-living materials we use to create our underwater habitats. Mostly consisting of wood, rock and substrate, it is important to choose natural materials as these will give our aquascapes an authentic feel. 

Being a natural product, no two pieces of wood or rock are the same. For example, some woods will release large amounts of tannic acids (tannins) into the water, giving the aquarium a darker, more natural appearance and lowering the pH of the water. Whilst these tannins are often beneficial to the aquarium inhabitants, they are not always desired by the aquascaper, so selecting a wood which has a minimal tannin release may be preferential. Let’s run through some of the most popular woods available and explore their characteristics.

Redmoor or Spider wood 

Redmoor is an aquascaping classic. Its shaped roots and branches are perfect for creating that underwater jungle feel — imagine small fish passing through the twisted roots as they reach into the open waters. 

Often available in a huge range of sizes from bags of spindly detailing twigs to enormous ‘stumps’, Redmoor is a great wood for creating detailed and high impact hardscapes. Redmoor can release quite high tannin levels, and is also prone to harmless but unsightly white fungal growth in the first week or two after submersion. 

River wood

River wood is one of my favourite woods to scape with. It has a real aged feel and comes in many different shapes and sizes, from small 10cm detailing pieces, to large branches. I have found it releases minimal tannins and is usually quick to become waterlogged. River wood is also quite a hard wood which will not rapidly decompose and will be enjoyed by rasping plecos.

Corbo catfish wood

As with River wood, Corbo catfish wood releases minimal tannins and is usually quick to sink. This wood is the perfect centrepiece. With its thick trunk and many protruding branches, it can be placed without the need for combining differently sized pieces and offers maximum impact for minimal creative effort. Ideal for those who are just starting out on their aquascaping journey. 

Corbo catfish wood is so called for its hollows and crevices, offering the perfect hidey-holes for shy catfish. These features also lend themselves well to placement of plants such as Anubias, Bucephalandra and Leptochilus species.


Manzanita is an incredibly beautiful wood found almost exclusively in California, USA. Long, gnarled branches can be combined to form truly stunning hardscapes. The thinner branches and twigs can also be used as fine detailing, for those aspiring to take their ‘scapes to the next level. Manzanita is a hard wood which will resist decay and last for a long time submerged in water.


One of the most popular and enduring aquarium decorations, Bogwood is a dark wood which will release heavy tannins and acidify aquarium water. This can be minimized by boiling or pre-soaking. 

Consider carefully when ordering bogwood online, as quite often this wood is lacking in character and can be unattractive lumps. Asking the retailer for advance pictures of the piece you’ll be sent would be a wise move. Having said that, there are some truly beautiful and dramatic pieces out there, for those determined to track them down.

River wood is smooth and aged.

Millennium tree /Azalea root

Millennium tree is one of the most dramatic and stunning woods available right now. It has many thin roots twisted together to form thicker trunks and branches. Usually available in bigger sizes, this isn’t the best choice for nano tanks. 

I have seen some truly mind blowing large aquascapes created using this wood but proceed with caution — there are anecdotes suggesting that it has been responsible for livestock deaths when not properly soaked for several weeks. Use with caution and always make sure you have soaked this wood thoroughly before adding any livestock to the tank.

Putting the ‘Hard’ into hardscape

Should we  choose detailed, cracked rocks with an aged feel and sense of scale, or do we opt for a rounder stone, with a truer to life water-eroded form? 

There’s also the consideration of how these rocks will affect the parameters of your water. Some rocks will add minerals, which is not desirable for many of the fish we keep. A good way around this is to choose your fish to fit your aquascape, if the main focus is to be the scape itself. Let’s take a look at a few of the most popular rocks and their characteristics.

Seiryu stone / Mini landscape rock

Seiryu stone is an aquascaper’s dream. It’s incredibly detailed, displaying cracks and crevices, plus it has white veins cutting dramatically through it. It’s also astonishingly versatile and comes in a variety of sizes. Small rocks can be used in nano tanks or as detailing in larger tanks, while the huge rocks, sometimes available at more than 30kg, can be used in giant aquariums. Take care with fish with delicate fins as Seiryu can present sharp edges. Also be aware that it can raise water hardness over time, though this is usually mitigated with regular water changes.

Black lava rock

If you’re looking for an inexpensive and easy rock to ‘scape with then lava rock is your friend! It’s lightweight so the price per kilo is great, and having no discernible strata makes it easy to work with. These rocks can be placed in almost any orientation, and sit well with their counterparts. They can be stacked easily and look natural when placed atop one another. Something to look out for; lava rock can range from grey to dark black, so if you’re particular about colour then it’s best to visit a shop in person or speak to your online retailer before ordering. Lava rock is inert and will not affect your water parameters.

Dragon stone

Dragon stone is a clay-based rock with many hollows, holes and a directional nature to the patterning. Perfect for creating diorama type layouts. This rock can be used to great effect when large pieces are used as the main focal point. It will not harden your water, but care must be taken when using with delicately-finned fish due to sharp edges.

Elderly stone

Elderly Stone is relative newcomer to the aquascape scene, with flat sides and deep cracks and crevices. Available in a variety of sizes it is ideal for both nano aquariums and larger tanks. 

This stone is dense so keep an
eye on those scales when selecting pieces as the cost can get high, fast! If I was asked to name my favourite stone to aquascape with, at the time of writing, I would say this one.

Scottish boulders / Pebbles

These can be used to great effect when designing a natural riverbed or hillstream style layout. Having been eroded smooth over thousands of years, these are how you see rocks
in fast flowing streams in nature. Mixing sizes and adding river-blend gravel to the pockets between rocks adds to the authenticity. Scottish Pebbles have little to no effect on water chemistry.

Where to start?

I hear a lot of people say, ‘I’d love to create a layout like this, but I wouldn’t know where to start’ and I always respond by explaining that many of the top aquascapes they see are created by people with years of experience, and often training, under their belts. 

However, it is entirely possible — easy, even — to create your own stunning hardscape layouts using a few basic rules and guidelines.

Start with a focal point. If you’ve selected one piece of wood or rock that really stands out to you (often the largest) then this should be positioned first. Avoid placing this focal point directly in the centre of the tank or too close to the edges. 

As in photography, we use the ‘rule of thirds’. Imagine dividing your aquarium up into thirds, both vertically and horizontally. Place your large focal point one third of the way along the length of the tank and build up your hardscape from there. This will give you a much more naturalistic and pleasing-to-the-eye layout, though there are some exceptions to this asymmetric rule — island-style ‘scapes often feature their hardscape and planting directly in the centre of the aquarium. However, you can still use the rule of thirds vertically to layer your hardscape from the bottom up.

Create depth. Many of the super impressive diorama style aquascapes use perspective to great effect. Try placing large objects at the forefront and gradually reducing the size of the hardscape until the branches and rocks become so small that they are almost at a vanishing point at the rear of the tank. Then, with the addition of a cleverly-placed meandering path, you can be fooled nto thinking the aquarium with a 50cm depth is several hundred metres deep! You don’t need to go to these extremes to create a sense of exaggerated depth, though. Try positioning large roots close to the front and thinner roots further towards the back, making sure all are visible when viewed head-on. On paper, this placement technique can seem counterintuitive — but trust me, it works!

To add a greater sense of depth to your ‘scape you could also bank your substrate deep towards the back. Use a less expensive media such as JBL Pro Scape Volcano Mineral as a base layer on which to add your planting soil. This will build up the height without the inevitable aquasoil landslide. Crushed lava rock also works for this, and provides a healthy environment where beneficial bacteria can thrive, so you can really go deep at the back!

Stick to one type of stone. It can be tempting to start mix all kinds of rocks, but this rarely looks good. In nature you will often only find one main type of stone. Some will be large, while others will have broken down or become eroded. It is this variation in size, not type, which will give your rock layouts real world feels.

If you’re after a neater, more formal layout, consider an Iwagumi style. Iwagumi uses stone as the sole hardscape material. Often centred around three well placed rocks of differing sizes, and surrounded by a carpet of lush green plants, it’s a stunning layout format — but it is not as easy as it looks. Rocks must be carefully placed at just the right angles from the substrate and from each other. As the only focal points, rocks matter, too. Choose the best you can find.

Pebbles are water-worn

It’s all in the details

When you’ve got your main hardscape laid out and you’re happy with the placement then it’s time to bring it up to the next level with some fine details. 

Use Redmoor or Manzanita to bring an aged look. Place thin branches over rocks, trailing down into the substrate — this will give the impression that the stones have been in place for decades, the surrounding tree roots searching out the path of least resistance to the soil. Utilise natural cracks and crevices in the rock, and these will help hold the branches in place without the need for superglue.

Add smaller rocks to the base of larger stones. I often choose a ‘sacrificial stone’ to smash up with a hammer (wear eye protection!) creating lots of small chippings to scatter. You may also consider using different grades of gravel to the same effect. Remember, adding cosmetic sands and gravels should be the last process before planting and filling. Moving large rocks or woods can easily mix your unsightly plant soils in with your pristine sands. Pack filter floss between gaps in rocks to prevent soil finding its way onto your sands.

Combining multiple wood roots to give the illusion of one epic piece is a great way to create something tailored to fit your aquarium. I have several techniques to achieve this, including using cable ties or fishing line to bundle wood together. 

Superglue is also wonderful stuff to have on hand. When using glue with hardscape, be sure that you are using cyanoacrylate with no nasty additives — if in doubt purchase from an aquascaping store. 

When using superglue for hardscape fixing, place a torn cigarette filter, or small piece of folded toilet tissue between the two pieces of hardscape you wish to join and squeeze on a generous amount of liquid glue. The bond will take a few seconds and will hold fast. To disguise the white join, you can add a little more glue and sprinkle on some crushed Dragon stone dust. 

Hardscape can be more beautiful than plants

Lastly, but by no means least, take your time. For me, building hardscape is one of the most exciting and creatively rewarding processes in aquarium keeping.
You are the architect, shaping your underwater world to not only be a happy, healthy home for the inhabitants, but also to present a beautiful spectacle in your home. 

Ultimately aquascaping is a way to relax after a long day at work and a way to wow guests at the weekend. Try to immerse yourself in the process, take progress photos, and if something isn’t right, don’t be afraid to change it. Just remember, once the tank is filled with water and the fish and plants are in it becomes an order of magnitude more difficult (and messy) to alter. 

Sleep on your design. If you’re still in love with your layout and haven’t touched it for three days, you’re probably good to go!