The picture above shows farm tanks in a shop in Japan. Inert coarse sand is used in holding tanks due to frequent uprooting of plants for sale.
When it comes to substrate, we are faced with a dazzling array of choices. For details on the different types of substrates, please go here. When it comes to making a choice, there are basically 3 key parameters to consider: ease of management, impact on plant growth and cost. One must ultimately prioritise what matters more.
DIY SOIL SUBSTRATES
Easy to manage, Cheap but mediocre impact on plant growth.
Easy to manage, Great for plant growth but expensive.
Cheap, Great for plant growth, but harder to manage.
Just Starting Out?
For people that are just starting out, and are uncertain of what type of aquascape they will build into, or where they will want to place certain plants, using an inert substrate allows plants & hardscape to be moved about easily without much mess. For new active aquascapers, the important part is that this approach encourages experimentation & learning. This is the default choice for many planted shops for their holding tanks - where plants are frequently uprooted to be sold. It is also much easier to keep clean.
A planned aquascape with mostly permanent planting
If you are building with an aquascape in mind:
Aquasoils (Tropica is easy for beginners)
Dirt with cap (lean top soil 1-2 inches with coarse sand cap 0.5 - 1 inch)
When there is some expectation of permanence and getting optimal plant growth is a priority, aquasoil / dirt with cap can be used in planted areas, with cosmetic sand in areas that are not fully planted to match hardscape settings. Mixing substrates means more work during setup, and also to keep the layers separate during replanting.
Growing easy or difficult plants?
If your aquascape is composed to easy-to-grow plants, go for inert substrates which are easier to manage. Harder plants? If you want every edge possible, choose aquasoil.
Beginners that intend to replant a lot will do better in inert substrates. This also makes moving hardscape easier. Dutch style aquascaping that requires very regular topping and replanting may also consider using inert substrates.
Discipline to dose regularly?
Are you prepared to dose every other day? Is regular dosing a chore? If yes, use aquasoils/ garden soil /dirt. When combined with root tabs, this combination allows more leeway in water column dosing.
A lush 120 gallon planted tank by Joe Harvey, using plain gravel (black diamond blasting sand). Read his very informative journal here. A great demonstration of management techniques.
Even expert growers such as Tom barr who dose their water column with nutrients very regularly still make use of aquasoil.
What about soil cleanliness in soil based planted tanks?
Dirt/soil based planted aquarium can be still kept very clean through these steps:
Where possible, prune without uprooting the entire plant. By allowing bottoms to regrow instead of replanting, it reduces the need for constant replanting.
Uproot plants slowly by first shaking side to side to loosen the root's grip on soil: avoid pulling vertically in an attempt to yank the plant out in a single move.
Lightly vacuum the substrate's surface using a slow pump every time replanting is done.
Use different cap thickness: in areas where plants have very deep roots, use a thicker substrate cap. In areas where plants have short/delicate roots, use a thinner substrate cap.
Many delicate carpets grow better in finer substrates. Hemianthus callitrichoides "Cuba" the a delicate foreground plant featured here. The red plant is Alternanthera reineckii mini, and it grows far better in soil-based substrates than inert ones.
For detailed care guide to aquarium plants above and more, click here.