Underwater Forest

April 2018

This incredible, planted aquarium is installed in a cave under a lake in the garden of a Private Client. The tank itself takes up an entire wall of the cave, and at almost 6 metres long & 2 metres deep, is the size of a cinema screen. It contains over 14,500 litres, making it the largest private planted tank in Europe.

Aquascape

The Client brief was to create an underwater forest scene, as if the viewer is looking out into the depths of the lake above. There are many issues to deal with when creating an aquascape on such a huge scale. We used real tree trunks selected not only for their beauty but also for their compatibility with aquatic life.

After looking at various species of deciduous tree such as birch and oak, we finally decided on Sweet Chestnut, due to its beautiful colour, straight trunks and interesting bark texture. Sweet Chestnut is also not toxic to the fish. We sourced these from a sustainably managed woodland in South-East England.

The trees have been painted with several layers of a polyurethane sealant. We’ve also created a structure to fix them securely to the base of aquarium. This way they will not float once submerged.

The planted aquarium is 1.5 metres from front to back, but we needed to create the illusion of looking much further into the distance. This was achieved by placing the largest trunks at the front, with increasingly smaller pieces towards the back.

To enhance this sense of perspective, it was important to slope the base of our aquascape upwards from front to back. In this case, we are using rocks to support higher levels of soil towards the rear of the tank, resulting in almost a metre of substrate against the rear glass, with only a few centimetres at the front. The spaces between the rocks provide terraces of soil for planting, while the rocks themselves can be used to attach other plants such as underwater mosses and ferns. Black lava rock is being used as it is lighter in weight than most other types of stone.

Finally, an off-centre path meandering into the distance and a light behind the tank provide final touches to the illusion.

Planting

To really understand how it feels to be enveloped by such a lush environment, we undertook a research trip to the temperate rainforests of South-West Scotland. Plant growth under the tree canopy here is incredibly verdant, with some of the highest annual rainfall in the UK. Many ferns and mosses dominate, covering most of the ground as well as growing over trees and rocks. We found some perfect reference material for our final aquascape.

Of course, the terrestrial plants we saw on our research trip would not survive long underwater. So, our next challenge was finding underwater species that look as similar as possible.

This was not the only requirement the plants must meet however. The water is slightly warmer than a normal aquarium, at 28-30 degrees Celsius, so they must be able to tolerate these higher temperatures.

We also had to consider how they must be maintained. At 2 metres tall, this aquarium is not easy to look after.  Underwater plants generally grow at much higher rates than other plants. Looking after them require a lot more trimming and pruning than your average garden.

Fish

The Client had a very definite view on the type of fish he wanted as the focus for the aquarium. When he saw pictures of brightly coloured Discus, he fell in love with them. Discus are a shoaling species from the Amazonian basin, which although visually striking, requires certain challenging conditions to be met.

The client was also keen on having a variety of bright colours, to contrast with the green plants. These captive-bred strains are available in a huge array of reds, oranges and blues. Keeping a large shoal of these amazing animals reduces any aggression between males, especially during breeding and provides safety in numbers.

We have also introduced over 600 Cardinal tetras, which in the wild, are also found in the Amazon basin.

In addition, there are hundreds of Cherry shrimps, algae-eating shrimps, dwarf catfish and snails as our ‘clean-up crew’.