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Best Overall: CaribSea Eco-Complete Planted Aquarium Substrate 20-lb bag
Eco-Complete has become one of the most popular substrates for live planted aquariums. It is composed of an extremely porous material that contains a wealth of nutrients as well as beneficial bacteria to support the nitrogen cycle. Among the key nutrients are iron, calcium, magnesium, potassium, and sulfur as well as two dozen other elements. These nutrients support robust root growth, while also promoting the development of healthy biologicals. No rinsing of the product is needed - it can be used as is in your aquarium. Eco-Complete is nitrate and carbonate free, and thus will not impact pH or carbonate hardness. This formula can be used as the sole substrate, eliminating the need for a layer of laterite as well as a regular substrate over it. It comes in two different colors (black and red), and they don't contain artificial dyes, chemicals, or paints. Sold in a twenty-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 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 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.