The substrate is the basis for any planted aquarium. Your choice regarding this element can define the success or failure of your project. When setting up an aquarium without plants, the choice can be defined mainly by aesthetics, but with a planted one it is necessary to consider numerous factors.
On a planted aquarium, we usually have a fertile substrate and also an inert layer, to separate the fertile layer from the water column. Both layers are fundamental and have their specific characteristics. The fertile layer is precisely where the roots of plants seek the nutrients they need to develop. The inert layer, on the other hand, prevents the water from becoming saturated with excess nutrients present in the fertile substrate, otherwise an algae explosion would arise, in addition to ammonia peaks that would endanger all life in the aquarium.
To choose the best substrate for the inert layer and the best one for the fertile layer, it is necessary to take into account many factors, such as granularity, nutrient concentration, durability, among others. There is no exact answer, as it depends on your goals and characteristics of your project. But let’s understand a little more about the role of each layer and also talk about some of the options available on the market. So you can make your choice with complete peace of mind.
Fertile substrate – Fixation, nutrients and durability.
When setting up your planted aquarium, you need a place for the plants to set their roots and absorb the nutrients they need to grow and propagate. This is precisely the function of the fertile substrate. Whether it is a natural substrate or an industrialized one, it will be full of the nutrients needed by plants, such as magnesium, potassium, calcium, phosphorus and sulfur.
You have two options for this layer, buy one of the industrialized substrates or use an alternative approach such as earthworm humus. Remembering that humus, although much cheaper, needs to be treated to be used without risk of damage to your aquarium.
Of the industrialized brands, some stand out and you can be sure that when you buy them you will have a great substrate, durable and that will provide the nutrients your plants need. Some great examples:
- Prodac Fertil Plant – Very cost-effective option. Cheaper but highly efficient. Requires an inert layer on top.
- Ocean Tech Plant Active – A little more expensive, but very good and practical. In theory, it does not need an inert layer. But using it as a fertile layer, with an inert layer on top, helps prevent algae outbreaks. In addition to that, in direct contact with water, it ends up degrading more easily.
- MBreda AmazonThe – Spectacular substrate, very practical, efficient, with many nutrients and durable. In addition, it is also very beautiful. No inert layer needed. One of the best substrates available in Brazil. But at a slightly higher price.
Inert substrate – What is the function and what needs to be considered.
The inert substrate has some functions, one of which is to give a beautiful finish to your aquarium. This substrate will be what will be visible in your tank, so it should look the way you want it, according to your vision for your setup.
But the inert layer also has another function, it is what prevents the fertile layer from leaking into the water column. A leak like this (depending on the substrate) can completely destroy your setup, as it will flood your aquarium with a lot of nutrients (which in high amounts, become pollutants). Care must be taken to ensure that this does not happen. The main thing is to use a good amount of inert substrate, on top of the fertile one. A layer of about 6 centimeters is usually used.
Another concern regarding this layer, in a planted aquarium, is that very thin substrates should be avoided, as they tend to compact more. A compacted substrate prevents the circulation of water and hinders the propagation of the roots, two factors that make the development of plants very difficult.
Inert substrates also influence plant fixation, so avoid lighter ones, as they make the planting process difficult, especially with plants that have small roots.
Some of the top choices for inert substrates are (links to buy on Amazon):
- pool filter sand – Cheap substrate, it looks very nice, depending on its mounting. It is necessary to be careful with the granulometry, because if it is not uniform, it can cause compaction. Easy to find at pool stores.
- Basalt – Good choice for those who want a dark and inexpensive substrate option.
- Gravel – Not a perfect option for planted aquariums. Because it can make it difficult for some plants to root. But it is used a lot and has a very cute appearance.
- industrialized substrates: There are many industrialized substrates that are simply beautiful. Some even come with special treatments that prevent the emergence of algae on their surface. One of the best brands in Brazil for these substrates is MBreda. Any branded substrate is of excellent quality.
Additives for fertile substrate.
Some aquarists, especially those focused on aquariums with high plant density, often add substrate additives to their setup. They use substances that will further increase the power of the fertile substrate. This is definitely not a necessity, but it can improve the development of your plants. It is very common, for example, in aquariums of the dutch style.
It is very common to use laterite, spread under the fertile substrate, which provides an extra load of iron (a very important substance for the development of your aquatic plants). There are also industrialized additives that add certain nutrients to the substrate. These must be applied to the fertile substrate during assembly, never afterwards.
Industrialized fertile substrate or homemade alternative?
If you are considering using a homemade substrate, such as earthworm humus, there are a few points you need to consider. These substrates have to go through a rigorous treatment process, so as not to bring anything harmful to the aquarium. It is always good to check its composition to avoid damage to its fauna and bacteria colony. Insulation care must be redoubled, as any slightest leak can be catastrophic for the aquarium and its inhabitants.
The use of industrialized substrates is much simpler, and ensures the proper distribution of nutrients, in the amount needed by your plants. In addition, there are options that can have contact with water, thus avoiding leakage problems. The only downside is that they are much more expensive. Therefore, weigh the benefits and risks, when choosing whether to use a homemade substrate, or an industrialized one.
Low tech aquarium – Use or not fertile substrate.
In a low tech aquarium, there is no need to have a fertile substrate, but if you have a very large number of plants, or are using some plants that are a little more demanding, it may be interesting to have them. An alternative would be to use fertile substrate only in the areas of the aquarium where the most demanding plants are. Another possibility would be to use fertilizer tablets, placed inside the inert substrate, in areas where there are many plants.
If you don’t want to use any fertile substrate, that’s no problem. Just monitor the development of your plants, if you notice any kind of deficiency, you can use liquid fertilizers to help them develop in the desired way.