Choosing a Planted Aquarium Substrate

 

If you are going to keep live plants in your tank, substrate choice is very important. This is because many plant species draw their nutrients from the substrate. If you ask around, you will probably find that there are as many different substrates used as stars in the sky. Many people swear by certain combinations or layering methods with various substrates. This article cannot go into every single possibility nor can it discuss the substrate choices for every species of plant. Each plant has different requirements and it is important that you know these requirements before setting up your aquarium.

 

What this article will do is point you in the direction of some common substrate aspects so you have a place to begin. You can then either stick with what works or experiment with your own combinations.

 

It should first be pointed out that not all plants require you to think about your substrate in great detail. You can successfully have a low-light tank without having to take the substrate into consideration. This is because many of the plants that survive in low light (such as Java Fern and Java Moss) are actually attached to the décor and not rooted in the substrate. Also, some plants could care less what substrate they are planted in because they obtain very little nutrition from their roots. However, this article will assume you are using plants that do extract their nutrients via their root system.

 

Price

 

The cost of the substrate is an important factor in your selection, especially if you have a large aquarium (the cost can add up fast). However, you will get what you pay for. You can choose to use gravel or some other cheap alternative, but many serious plant aquarists use substrates specifically formulated for plant growth. Examples include Fluorite and Eco-Complete. These products will provide your plants with a constant supply of iron, a very important nutrient in their growth. The main drawback to these products, however, is their expense. However, many people will tell you that the price is worth it.

 

Cheap substitutes such as kitty litter, dirt, or potting soil are not recommended for aquarium use. Some people do use these products with success, but more often than not, they lead to disaster. The first problem is that there is no uniformity to these products so you do not know if the substrate you put in last year is the same as this year. Secondly, they may contain harmful chemicals that can make your aquarium toxic. Lastly, these products can create a mess in your aquarium if a plant gets uprooted, for example.

 

One way you can cut costs is to mix substrates. For instance, you can provide a layer of the expensive stuff and then put layers of sand or gravel on top of it.

 

Particle Size

 

The particle size of your substrate is very important. It cannot be too small or the substrate will compact and the small roots will not be able to grow properly. It cannot be too large or a great deal of debris will be trapped inside it.

 

Gravel can be used as a substrate, but it should be the finer grained gravel (2-3 mm particle size) and you will need to fertilize it (typically with root tabs that you push into the substrate near a plant’s roots) since the gravel itself will not provide any nutrients. Also, a layer of peat or Laterite under the gravel is advisable to provide some nutrients. However, be careful not to disturb the top gravel layer as the bottom layer products can cause algae problems if leached into the water column.

 

Reactivity to Water

 

It is important for most plants that your substrate be inert. This is because most will thrive in a neutral environment. Therefore, substrates such as crushed coral or substrates that contain shells should be avoided. If you are in doubt then take some of your substrate and pour hydrochloric acid over it; if it bubbles or fizzes, it is not inert.

 

Aesthetic Qualities

 

The same principles apply to a planted tank as to a non-planted one. Darker substrates will make the plant colors stand out while lighter substrates will tend to wash the colors out. Keep this in mind when making your selection.

 

Anchors Well 

 

It is important that your substrate remains anchored to the bottom of the tank and is able to hold your plants in place. You do not want your plants to be floating up to the surface (unless this is your intention) nor do you want your substrate to be floating around your tank. If you do choose a substrate that does not remain at the bottom of your tank, you can put a layer of gravel or sand on top to keep it anchored down.

 

Depth

 

The depth of your substrate is important as it will dictate how much room your plants’ roots have to grow. Typically, you want to slope your gravel or build terraces with deeper substrate in the rear (5” or so) and shallower substrate in the front (3” or so). This not only provides the illusion of depth in your aquarium, but it also allows you to accommodate a wide range of plant sizes.

 

Conclusion

 

There are literally hundreds of choices that you can use for your planted aquarium’s substrate. This article is meant to provide a general introduction that will enable you to jump into your own experimentation. Using the points addressed in this article, try various combinations and just see what works best. Also, remember to carefully research your specific plants so you know where they get their nutrients from.

 

As a final note, with most substrates (especially the ones specifically formulated for plant growth) it is important that you rinse them before adding them to your aquarium. They can contain a large amount of dust and you do not want to introduce this mess to your tank.