Plant layers add vertical interest
Aquatic plants for aquaria are commonly classed by how tall they can be expected to grow, with the idea that it is sensible to grow the shortest plants at the front of the tank, middle-sized plants somewhat further back behind the shortest plants, and the tallest plants at the very back. In the community these are generally called, logically enough, foreground, midground and background plants. Of course, you don’t have to follow this scheme and there might be a specific effect you’re trying to achieve by putting taller plants in front of shorter plants, but ideally this would be a deliberate choice and not something you unintentionally discover by accident.
In this video, you can see the effect in action. On the left, at the very front bottom of the tank, low down and in the shadow of the lobelia, is a single dark green line of newly planted cryptocoryne lutea ‘hobbit’ which is expected to grow to a maximum of 5 cm. The aforementioned lobelia cardinalis ‘wavy’, bright green and filling the bottow left quadrant of the tank, was planted six months ago and has topped out at its maximum height of just under 20 cm. In the back of the tank, the red plant arching over the lobelia is ludwigia palustris mini ‘Super Red’ which would be around 45 cm if stretched out to its full length. The very low carpeting plant on the right side all around the base of the mountain is marsilea hirsuta (although if you look carefully, there is another ‘hobbit’ hiding in the bottom right front corner. The marsilea was planted over a year ago and will never get any larger than it is currently. Some people like the look of plants that float on the surface such as frogbit or duckweed, and in a larger setup these can be effective, but I prefer not to go there in this instance.
I like the look of the different horizontal layers of plants on the left, contrasting with the verticality of the mountain sculpture on the right. The fish seem to appreciate the differences too – if they’re nervous they can hide under the lobelia, or explore above the lobelia while still feeling a degree of sheltering protection (or at least so I project upon them) from the overarching ludwigia.