Selecting the Right Substrate for your Planted Tank

Selecting the Right Substrate for your Planted Tank

Your substrate will form the foundation of your planted tank’s ecosystem, and it’s imperative to select the right one for your needs. As the planted tank hobby has grown, a number of commercial substrates have come onto the market.

This guide discusses some of the more common brands and their benefits and drawbacks, and also gives some tips and tricks for substrate selection and addition.

Substrate brands

ADA Amazonia Aquasoil

ADA Amaozonia Aquasoil is made from baked soil granules that contain macronutrients plants draw upon as they grow. It contains other beneficial nutrients to help plants develop an extensive root structure.

Aquasoil also lowers your tank’s pH and KH, so is ideal for planted tanks and fish species such as discus that require soft, acidic water. The dark color of Aquasoil provides an excellent contrast.

Aquasoil is one of the better premium substrates going, but it also has some downsides. When it is rehydrated, it makes the water very cloudy for a few days. It can also leach ammonia; you’ll want to rehydrate and rinse this substrate in a separate container before adding it to your tank.

The nutrients in Aquasoil are exhausted within a year, so you’ll need to dose your planted tank with fertilizer and/or add new substrate after this time.

Mr. Aqua Aquarium Soil Substrate

Like Aquasoil, Mr. Aqua is made of nutrient-infused, granular soil, and has many of the same benefits and drawbacks. Mr. Aqua reportedly does not leach as much ammonia into the water column as Aquasoil. It also keeps its form for longer, so does not need to be replaced as quickly. However, the nutrients are exhausted in about the same amount of time.

Fluval Plant and Shrimp Stratum

Fluval is a pelleted semi-soft clay, and has similar chemical properties to Aquasoil and Mr. Aqua.

As promised by the name, Fluval is particularly well-suited to shrimp, particularly if you’re looking to breed them. The babies can shelter in the sediment of the substrate until they’re ready to emerge. It’s also excellent for ground-covering plants with shallow, delicate root structures.

Fluval stratum has similar benefits and drawbacks to other soil-based substrates. It’s reported to lose its buffering capacity more quickly, so may not be ideal if you’re using tap water, particularly if it’s hard and alkaline.

Seachem Flourite

Seachem Flourite is a gravel made of porous clay. Flourite is inert on its own, but absorbs fertilizers added to the water column or substrate and disperses them over time. This has been likened to charging a battery – fertilizing your tank “charges” the flourite, and the charge is gradually released over time. Flourite also does not break down, so lasts longer than the soil-based substrates.​

The sharp edges of flourite make it very easy to plant in, as it grips plants’ root structures and holds them in place. You won’t need weights when planting in flourite.

The drawback to flourite is that it does not promote rapid plant growth like the nutrient-infused substrates, although it also does not leach macronutrients into the water column. Like other substrates, flourite can cloud the water when it’s first added to your tank, but rinsing first should help with this.

CaribSea Eco-Complete

CaribSea Eco-Complete can be considered a compromise between flourite and a soil-based substrate. It is made from volcanic soil, and like flourite is very porous and absorbs nutrients. However, it is not completely inert, and contains micronutrients and iron to help facilitate plant growth. It does not, however, contain macronutrients.

Eco-Complete also contains denitrifying bacteria and Amazonia black water extract, so helps to cycle and condition new tanks. An additional benefit of Eco-complete is that it comes pre-rinsed and does not cloud water.

The only real drawback is that the inconsistent size of the granules can make it difficult to build lasting hills and slopes when aquascaping. It also does not promote rapid plant growth like soil-based substrates.

Selecting and Adding Your Substrate

The right substrate for your planted tank will depend on a few factors, including the plant, fish and invertebrate species you plan to keep, what fertilization regimen you intend to use and how long you’d like your substrate to last prior to adding more.

Many aquarists recommend using a combination of substrates to get the best of both worlds. Flourite is longer-lasting than many other substrates, and its hard consistency provides a good foundation. Some aquarists recommend using flourite as a foundation and adding one of the soil-based substrates on top. To cut costs, you can also use regular gravel in lieu of flourite for this type of setup.

The appropriate depth of substrate will depend upon the brand of substrate and your aquarium’s gallonage and dimensions. The Planted Tank has a very helpful substrate depth calculator that can help you determine substrate depth, although it does not include soil-based substrates.

Prior to adding any substrate, be sure to read the manufacturer's instructions fully, and rinse the substrate in a separate container. Also keep in mind that the nutrient-infused soils will leach macronutrients into your water for a few days, which are toxic to fish and invertebrates.

Have any insights, tips or tricks on substrate selection or addition? Please leave them in the comments below!