2hr Guide to Iwagumi aquascapes

Seiryu rock aquascape with dwarf hair grass (Eleocharis acicularis)

Introduction

Iwagumi layouts are rock-focused planted aquariums inspired by Japanese and Chinese rock gardens and Japanese / Chinese rock appreciation - (水石) Suiseki in Japan and (供石) in China. Their aim is to showcase particularly aesthetic pieces of rock; rocks with interesting weathering patterns or shapes are good candidates for such aquascapes.

At their most purist, Iwagumi layouts use only a single type of rock and plant, and usually consist of an odd number of aesthetically pleasing rocks (3 to 9 pieces). The rocks are arranged in a format where the smaller rocks echo and complement the textures and directionality of the main rocks. A single type of plant is usually planted around the rocks to completely carpet the tank.

The modernist approach is more complicated - main rocks are mixed with smaller rocks to create a more naturalistic transition from larger rocks to substrate. Instead of individual rocks, larger rock formations and ridges can be created. Instead of planting all the substrate, areas can be planted with cosmetic sand, and instead of just a flat substrate, the landscape can be sculpted into hills and slopes. Even the choice of plants can be more varied - using a mix of plants rather than a single species.

Iwagumi aquascape by Jurijs

Guide to rock selection

1. Size of main rocks

The largest pieces of rock in a tank should be at least 3/4 of the height of the tank, if not more, to create a strong impression. The bottom few inches of large rocks are usually buried in the substrate to give the impression that the rocks are rising naturally out of the ground. Tilting rocks to get a more aesthetic angle also reduces the final height of the rock. Most hobbyists use rocks that are far too small - underestimating the size needed to make the hardscape stand out in the tank.

Smaller pieces of rock can also be joined together to form a larger rock formation. However, this process can be tedious and requires a fine eye for matching the textures of individual rocks.

In this example, we use a rock about half the height of the tank. The rock will visually shrink after being placed in the pool. The hardscape will continue to shrink as the carpet grows and covers the bottom of the rock. The final hardscape is far too small for this size of pool.

In this example we are replacing the rock with another piece that is 3/4 of the height of the tank. When placed in the tank, the rock is large enough to make an impact - but after the carpet has grown in, the hardscape will probably be just large enough to hold its own. What looked like a huge piece of rock outside the tank will appear to be of average size when used in the aquascape.

We try to replace the rock with an even larger piece that is about 80% of the height of the tank. Tilting the rock to create an attractive shadow reduces its final height considerably. However, this rock will still carry good weight in the final layout and will still stand out when the tank is fully grown in.

2. Shape, Texture

Triangular pieces are easier to arrange than square or round pieces, but do not let this limit your creativity. Rocks with unique textures and shapes are the best candidates for main rocks, but rocks with very unique shapes and textures are harder to match. Finding rocks with matching textures is important for the whole aquascape to come together as a whole.

3. Variety of matching rock sizes

In nature, larger rocks are constantly breaking down into smaller pieces. Where there are large rocks, there will usually be smaller rocks of a similar type. Having a mix of smaller rocks is very important when making a more modern style of Iwagumi, where larger rocks transition smoothly into smaller pieces. This is especially true for Iwagumis where sand portions are used. Smaller pieces are necessary for a natural looking transition from larger pieces to the substrate. Some types of rock (ohko, lava rock, shale) can be easily broken into smaller pieces with a hammer. Others (Seiryu, limestone, granite) are very hard and difficult to break by hand.

Arrangement Tips

Not all views of the same rock are equally aesthetic. The rock may also look best at an angle other than its natural resting angle, and smaller rocks can be used to support rocks to expose their best face to frontal view. Cracks, interesting rock textures and other aesthetic features make good focal points.

More significant pieces of rock should be tilted at an angle so that the downward facing face is in shadow. This shadowed surface contrasts well with the brighter surfaces directly facing the light and gives the rock a more three-dimensional appearance in photographs. Shadows will also contrast well with sandy areas and more open areas - and such contrast is important in an aquascape. Rocks with flat faces that are evenly lit will look flat and unattractive in photographs. Diagonal lines created by angled rocks in an aquascape give a sense of movement and excitement, whereas square rocks look stable and boring.

Smaller pieces should match the larger pieces somewhat so that the aquascape comes together as a whole. This can be done by creating a pattern that runs through the whole layout - for example, by tilting all rocks at a similar angle or using rocks with similar textures.

Example:These rocks look rather boring, don't they? The faces are all flat and unexciting. They look like a set of very uninteresting rocks, unworthy of a sophisticated Iwagumi aquascape.

The same set of rocks tilted at an angle after choosing the most aesthetic surface for each rock. The lightly shadowed bottoms contrast nicely with the light textures on top. Tilting the rocks in a similar way brings unity to the three separate rocks.

Add another smaller rock (on the far left) to complement the main rocks. Now the main rocks are united by a similar angle of inclination and the smaller rocks echo the shape of the larger ones, bringing the structure together as a whole. More smaller rocks are added to give a more natural transition in the size of the rocks and to provide a contrasting texture to both the sand and the larger rocks.

Finer pieces of rock are added at the base of the larger rocks to ensure that the whole rock structure blends well with the substrate. Here we have a good naturalistic gradation of rock sizes from large to smaller pieces. Strong shadows contrast with both the sand and the lighter rock faces.

Aquasoil or sand?

The area to be planted should be filled with aquasoil rather than sand. This allows us to supply nitrogen and phosphorus to the carpet plants in the substrate without adding either nutrient to the water column. Minimising nitrogen and phosphorus in the water column reduces the development of green algae on the rocks and allows us to maintain clean, algae-free rocks with less effort. If we were to use an inert substrate such as sand, we would need to add more nutrients (especially N and P) to the water column and this would encourage the development of green algae on the rocks.

Suitable carpeting plant species

Dwarf hair grass (Eleocharis acicularis, Eleocharis parvula)

Dwarf hair grass has long been a staple of the aquarium hobby. The plant grows as dark green strands that spread quickly through underground runners. Eleocharis acicularis tends to grow more vertically, giving a slightly taller carpet than Eleocharis parvula, which has slightly shorter leaves that fall sideways. Both species are hardy plants that can tolerate poorer growing conditions than more sensitive species such as HC.

The taller growth form of dwarf hairgrass compared to the flatter tufts of MC and HC also allows it to hide the base of rocks more easily. This can smooth the transition from rock to substrate.

Eleocharis acicularis carpet with Seiru rock.

Eleocharis parvula carpet, Seiryu rock aquascape - tank size 120x45x45cm.

MC (Micranthemum tweediei 'Monte carlo')

Monte Carlo is a light green carpet plant with round leaves on a creeping green stem. It is hardier than the smaller HC and has a moderate growth rate. It can even be grown without substrate by gluing it to flat rock or wood surfaces. Monte Carlo is the best candidate for aquariums without CO2 injection and, together with Dwarf Hairy Grass, is the two easiest carpet plants to grow.

The light green tone of the Monte carlo foreground in this "dutch style" aquascape gives a nice contrast to the red stem plants in the back.

Monte carlo carpet, the larger leaved plant is Staurogyne repens.

HC (Hemianthus callitrichoides 'Cuba')

Hemianthus callitrichoides 'Cuba', or HC for short, is one of the smallest of the aquatic carpets. The light green carpet spreads quickly under good growth conditions. It requires adequate CO2 levels to grow in good condition. Compared to Monte Carlo, HC has thinner stems and is a much more delicate plant. It is much more difficult to grow well than Monte Carlo or Dwarf Hair Grass.

The small leaves of HC contrast well against the larger leaves of most other aquarium plants.

Neocaridina shrimp less than an inch long on HC carpet.

Monte carlo left top and HC bottom right. HC has smaller leaves.

Glosso (Glossostigma elatinoides)

Glossostigma elatinoides has round green leaves on an elongated petiole. This plant spreads very quickly by runners when growth conditions are good. Each runner node usually produces a set of 2 or 3 leaves. Due to its rapid growth, this plant will quickly cover even large aquaria. It requires a little more light than Dwarf Hairy Grass to grow well and does best in CO2 injected aquariums.

UG (Utricularia gramminifolia)

Utricularia gramminifolia has short, light green leaves that are much wider than those of the dwarf hairgrass. UG is a bladder wort - a carnivorous plant that produces tiny bladder traps to catch microscopic prey. Similar to other carpet plants on this page, the plant reproduces rapidly by runners. These runners will tunnel through soil/aquasoil but will also adhere to hardscape and other rough surfaces. UG can easily be grown on hardscape or floating if you do not want to use it as a carpet on the substrate.

Although Utricularia gramminifolia produces bladder traps, these traps are harmless to shrimp and fish. The plant does not need to be fed manually and, unlike other carnivorous plants, UG can grow in fertile substrates and is not as sensitive to fertiliser. However, it prefers to be planted in a biologically mature aquarium. People who plant it in fresh setups often find that it melts. Compared to the other carpet varieties, UG can be more difficult to trim as it quickly forms very dense mats. The foliage is also more delicate and the plant needs a more stable tank to do well in the long term.

Strategy to avoid algae in an Iwagumi aquascape

1. Feed carpeting plants N and P from the substrate

Substrates that provide carpets with the macro elements nitrogen and phosphorus allow us to use water column fertilisation without these two elements. In our Iwagumi tank examples above, we use APT 1 in the water column, which contains all nutrients except N and P. Completely depleting the water column of N and P minimises algae growth on sand banks and hardscape.

2. Use low light levels

Many people think of carpet plants as plants that need high light levels to grow and spread, but this is not true. Any carpet plant, from Dwarf Hairgrass (Eleocharis acicularis/parvula) to HC (Hemianthus callitrichoides 'Cuba'), MC (Micranthemum tweediei 'Monte Carlo') can spread with as little as 20+ umols of PAR as long as CO2 injection is provided. We recommend substrate levels of 30-60 umols PAR, but no more. This will keep algae to a minimum and keep white sand areas and rocks in their original colour.

This 4ft Iwagumi has around 50umol PAR in the centre and 30+umol PAR on the sides. APT 1 is the only additive added to the water column for plant nutrition. 50-80% weekly water changes.

This 2ft Iwagumi has around 40umol PAR in the centre and 30+umol PAR at the edges. APT 1 is the only additive added to the water column for plant nutrition. 50-80% weekly water changes.

3. Keep organic waste levels low

In planted tanks, where there is a dominant amount of larger plants occupying most of the ecological space, the tank becomes naturally resistant to algae as the higher plants out-complete the algae. However, in Iwagumi setups the amount of plant mass is low and we cannot rely on plant mass to defend the tank against algae.

Elevated levels of organic waste can trigger algae even when light levels are already low. In lower light tanks this may manifest itself as cyanobacteria (BGA) or diatoms (brown algae). In higher light tanks it will show up as GDA (green dust algae) on the glass and rocks. Keep the level of organic waste low by keeping the fish stock light where possible and making more water changes to keep the water quality high. During water changes, it is important to siphon off detritus from the substrate surface.

 Clickhere on how to water change the 2hr Way.

Iwagumi aquascapes that use too much light and/or have high nitrate/phosphate levels in the water are more likely to get green algae on the hardscape. Carpeting plants will spread more quickly in a high light, high water column nutrient tank, but at the expense of hardscape cleanliness.

Putting a system together

Equipment list

Filter: Oase Biomaster 250

Light: Week aqua T90, hung 4 feet above tank, 50% power

CO2: Injected through inline atomizer system, Aquatic farmer regulator

Fertilization: 2Hr Aquarist APT 1, 1ml per day.

Substrate: 2hr Aquarist aquasoil, cosmetic sand

Rocks: Seiryu rock

Foreground plant: Eleocharis acicularis

Fauna: Pygmy cories, White cloud mountain minnows

Maintenance regime: 

Weekly water changes of 50-70%, where detritus on the substrate level is siphoned away, water change 2hr Way.Cut the dwarf hair grass carpet every few months. Add APT Jazz Root Tabs to the substrate every 8 months or so. The Oase pre-filter is cleaned every 3 weeks and the main chamber is serviced only once a year.

Other regular tasks include the daily dosage of APT 1 water column fertiliser at 1ml per day. The CO2 system is checked regularly to ensure that CO2 levels remain optimal - adequate CO2 (25-30ppm) will allow the Hair Grass carpet to spread well even when low light levels are used.