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Issue: January 2008

Maintaining an Iwagumi Layout in the Nature Aquarium

Author: Takashi Amano

AMANO Feature 0108
Photographer: Takashi Amano
The master of the artfully planted tank divulges his secrets to keeping up with—and re–imagining—a rock–based planted aquascape.

In last month’s article I explained the basic method for creating an iwagumi layout. This month, I’d like to explain how to maintain the iwagumi layout once it has been created so that it may be enjoyed over a long period of time.
  In an iwagumi layout, only one type of rock is used as a composition material, and generally only a few types of aquatic plants are planted in a simple arrangement. Due to this simple composition, the strength of the presence of the rocks and their overall impression are influenced greatly by the arrangement of aquatic plants and the denseness of their growth. Therefore, the selection of the aquatic plants and the timing of their trimming are very important.
   Because of the strong presence of rocks, it is important to keep the rocks clean as well. In an iwagumi layout, the rock arrangement can be left intact while plants are rearranged. With the above considerations in mind, let’s explore the maintenance of the iwagumi layout over time.

Plant Arrangement
   In an iwagumi layout, if the rocks are hidden by aquatic plants, the presence of the rocks becomes weak, and the balance of the rock arrangement and the intention of the expression—such as the flow of water—become unclear. Therefore, aquatic plants that tend to grow tall should not be used, at least in front of rocks. It is the smaller plants, such as Glossostigma and Cuba pearl grass, that are suitable for planting in front of rocks.
   I sometimes plant somewhat taller plants such as hair grass and Echinodorus tenellus behind or around rocks. Besides these plants, I sometimes use willow moss and Riccia in an arrangement by wrapping them around small stones. These aquatic plants are suitable not only due to their smaller sizes, but also their resilience against repeated trimming.

   Although Glossostigma and Cuba pearl grass are small plants, they can form thick mats as they grow and hide small rocks from the view. And aside from the problem of the small rocks being obscured, if the mat becomes too thick, it overpowers the overall layout as well. Therefore periodic trimming and replanting become necessary to maintain an iwagumi layout according to its desired image. First, these aquatic plants are trimmed horizontally across the substrate using specialized trimming scissors (the type with curved blades is easier for this task), leaving a thin mat of runners and leaves.
   This type of trimming will suffice in the beginning. However, with repeated trimming, their roots tend to lift from the substrate and they stop developing new leaves quickly. When this happens, apply a powder-type enriched soil that matches the substrate type thinly over the plant. A fine, powder-type soil will get in between roots and runners and the plants will start growing vigorously again. This method is effective for rejuvenating hair grass and Cuba pearl grass as well.

Substrate and Plant Replacement
   If this method does not improve the growth of aquatic plants, it is necessary to take out and replant the aquatic plants. Replacing the surface layer of the nutritive soil substrate with new soil at this point encourages plants to grow vigorously again. Since rock arrangement is very solid in the case of an iwagumi layout, it is easy to partially replace the substrate and replant aquatic plants.
   The layout introduced here was completely revamped to a layout with a totally different impression by changing out the aquatic plants during replanting. In the Nature Aquarium style, this type of a planting change is called sozo haishoku (creative plant arrangement).
   In this layout, willow moss and hair grass were planted around the arrangement of seiryu-seki stones at the beginning. The layout was reborn through sozo haishoku to the one planted mainly with Riccia and stem plants. I introduced this layout here as an example of enjoying an iwagumi layout for a long period of time, although the impression of the layout as an iwagumi layout became weaker through sozo haishoku, with the plants hiding the rocks a lot more.
   I left the cosmetic sand in the foreground the way it was, removed the nutritive soil substrate material as much as possible, and replaced it with a new batch. If you remove fish and other livestock from the aquarium and drain the water completely to do the work, you can minimize collapsing of the substrate.

Algae Control
   Lastly, if you maintain an iwagumi layout over a long period, you will definitely have to face the issue of algae. You can remove algae either by frequently brushing rocks or using the biological method of algae-grazing livestock.
   There are a few types of algae that stick to rocks. At first, green algae emerges and covers an entire rock thinly. Then the algae that are more difficult to remove, such as black beard algae and calcareous algae, start to grow. To counteract them, you can either brush off the algae at the initial stage or add livestock that eat the algae. Snails such as Clithon retropictus are effective for this purpose. The Siamese flying fox is worth trying as well, if you have dark, stiff algae, since it is effective against that type of algae.

See the full article on TFH Digital

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