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Aquascaping & Decor


June 4, 2020 | By Tom Sarac

by Tom Sarac

Soil has become a popular substrate option these days, particularly for aquascapers and shrimpkeepers as its size, structure, dark color and shape offer a striking natural canvas in an aquarium. Soil substrates are produced by means of a special manufacturing process that involves high pressure and heat, and that converts mineral-rich volcanic soil into lightweight, granular, voluminous substrates. Soil helps to support conditions that all aquarists hope for: crystal clear water and an abundance of lush, healthy plants!

Perfect for Planted Aquariums

There are a number of soil substrates available on the market, but they aren’t all created equally. Superior soil products include those that have been sourced from volcanic areas, such as Fluval Stratum, which originates from the foothills of the famous Mount Aso volcano in Japan. Volcanic soil substrates contain a number of beneficial compounds, such as potassium and iron, which greatly benefit plants. Furthermore, some soil substrates contain a phosphorous compound that helps support the slightly acidic water chemistry that most plant species prefer.

Roots systems fulfill an important function for most plants beyond just acting as an anchor point. Aquatic plants use their roots to extract nutrients from the substrate (some species more than others), which are then transported upwards through the stems. The light structure of soil substrates allows growing roots to easily extend throughout them – in contrast, dense, hard substrates such as gravel can impede plant root growth and inhibit the establishment of a healthy root system.

Fish considerations

As attractive as soil substrates are, they are more suitable for some species of fish than others. In general, soil is a better choice for aquariums featuring smaller, more delicate species – dwarf and smaller species of tetras, rasboras, anabantids, livebearers and dwarf cichlids are safe choices. Soil substrates are not recommended for goldfish, large cichlids, large species of catfish, loaches or any digging species that are known to spend time rearranging the bottom of an aquarium.

Setting Up, Life Span and Maintenance

When first setting up an aquarium with a soil substrate, some hobbyists prefer to not rinse the soil at all and instead slowly fill the aquarium to avoid disturbing the substrate. While this can work, it is not recommended, as it can ultimately result in the aquarium being heavily clouded for over a week. The alternative and recommended approach is to gently rinse the soil in small batches with a colander. This will reduce cloudiness once the aquarium is filled, as the fine particles that would have otherwise been suspended in the water are flushed away. Furthermore, rinsing soil substrates will not diminish the nutritive content of the soil in any way. Once the substrate has been rinsed, filling the aquarium slowly and carefully is still recommended.

If mixing a soil substrate with another kind of substrate (sand, gravel, etc.), exercise caution, as doing so can result in the soil breaking down prematurely. In general, the soil should be placed on top of other substrates due to its fragile nature and in order to gain the benefits of its porous structure. A better alternative is to create a physical division between the substrates: for example, soil in the rear of the aquarium, to benefit the plants, and inert sand in the front, for aesthetic purposes. This will facilitate maintenance and will ensure the full lifespan of the soil, which is typically 1.5 to 2 years.

Maintaining a soil substrate is easy! A light siphoning above the substrate every week or two when performing a partial water change is usually adequate, especially given the types of fish that are typically kept in aquariums with soil substrates. A product such as the Fluval 3-in-1 Waste Remover / Feeder (Small, Large) can be used to dislodge debris / detritus / waste from the soil, which can then be more easily removed from the aquarium with a small hose. Do not use a gravel vacuum to clean a soil substrate as one would with gravel or sand, as doing so will destroy the substrate.

A soil substrate is a wonderful choice for a planted aquarium and for tanks with shrimp! The benefits are numerous – why not try out Fluval Stratum in your aquarium today?

  • Lightweight: easy plant root growth and penetration
  • Voluminous: economic choice vs. denser clay-based substrates
  • Natural Nutrients: contains key macro elements essential to plant growth
  • Open Substrate Space: ideal habitat for shrimp fry and nutrient circulation for plants
  • Natural Compounds: supports slightly acidic pH and enhances water clarity


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