The right planted aquarium substrate won't alter your aquarium's pH, supports the beneficial bacteria that contributes to the nitrogen cycle, and has the micro- and macronutrients your plants need to thrive. We sought the best substrates with help from Nic Tiemens, co-founder of Infinity Aquarium Design, researching substrate options for their composition and ease of use.
Here are the best aquarium plant substrates.
Best Overall: CaribSea Eco-Complete Planted Aquarium Substrate 20-lb bag
CaribSea Eco-Complete Planted Aquarium Substrate is primarily composed of basaltic volcanic soil, which has a high granular absorbency that helps promote optimal nutrition uptake to your plant's roots. It also has the bacteria necessary to maintain your aquarium's internal nitrogen cycle, in addition to 25 other micro- and macronutrients useful to plants, including iron, calcium, magnesium, potassium, and sulfur. While supplemental fertilizer will eventually be necessary, Eco-Complete will provide the right start to your planted aquarium.
It's also easy to use. There's no need to rinse Eco-Complete in advance, simply fill the bottom of your tank to a depth of approximately 3 inches. The CaribSea substrate contains both fine and large grains, which will eventually settle into two separate layers, with a finer bottom providing hold for your plant's roots. While you always have the option of a second substrate layer, such as one selected for aesthetic cover, it's not necessary when using Eco-Complete, which has a neutral black tone.
CaribSea's Eco-Complete contains no artificial dyes. It is additionally free of nitrate and carbonate, so it won't alter the hardness or pH values of your aquarium water. It is available in a 20-pound bag.
Runner-Up, Best Overall: Seachem Flourite 15.4 lbs
Seachem Flourite is a porous clay substrate that is nutrient rich, particularly in iron. It can be used as a stand-alone substrate in a freshwater aquarium without the need for additional plant nutrients supplements. It is not chemically treated and is pH neutral. Seachem Flourite comes in 15-pound bags and is available in a natural dark color, red, black, and black sand.
Best for Live-Planted Aquariums: Fluval Plant and Shrimp Stratum
Fluval Plant Stratum is a lightweight porous substrate intended for use in freshwater live planted aquariums. It is formulated to support nitrifying bacteria and maintain a neutral to slightly acid pH while not discoloring the water. It will not compact and allows roots to grow and spread readily throughout the substrate. A variation of this substrate is made specifically for shrimp tanks. The color is designed to camouflage newborn shrimp from fish, and the grain size is small enough for them to hide in. This substrate is not recommended for large or boisterous fish, such as large cichlids or goldfish, nor is it intended for use in brackish tanks.
Fluval Plant Stratum, should be lightly rinsed to remove loose dust. The tank will initially be cloudy; however, it is safe for fish and shrimp even during the cloud stage, and will clear in a matter of hours. It is not recommended to mix this substrate with gravel or other substrates. Fluval Plant Stratum comes packaged in 4.4-, 8.8- and 17.6-pound bags. A single 4.4-pound bag is suitable for tanks under 18 inches, while an 8.8-pound bag is suitable for 18-inch tanks, and the 17.6-pound bag will cover a 24-inch aquarium.
Best for Nitrification: Activ-Flora Lake Gems for Aquarium, 20-Pound
ActivFlora™ Planted Aquarium Substrates are specialized gravels that contain essential minerals, micro-nutrients, and heterotrophic bacteria to support healthy nitrification processes. It can be used as the sole substrate and is pH neutral. Available in several grain sizes and colors for use in a variety of applications.
Our top pick of substrate for plants in a freshwater aquarium is CaribSea Eco-Complete (view at Amazon).
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This article was written by Shirlie Sharpe, is a fish and aquarium expert who has written a book on setting up an aquarium
For additional background on aquarium plant substrates, we spoke to Nic Tiemens, co-founder of Infinity Aquarium Design, who spoke about what to look for in substrates.