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    Fertilizing substrate

    An overview of fertilizer balls and tabs

    In addition to liquid fertilization aquatic plants can be nourished pointedly via their roots. This is usually done with a nutritious substrate such as soil. To further stimulate certain plants significantly in growth or to enrich otherwise nutrient-less soil substrates such as gravel or sand with fertilizer, substrate fertilizers in the shape of balls, tabs or sticks are popular.

    The various aquatic plant species absorb nutrients in varying degrees via their leaves, stems and root system. Above all, aquarium plants which are strong root-eaters profit very much from a specific substrate fertilization. These include, for example, Crypts, Echinodorus or Vallisneria.

    Various nutrients via substrate fertilization

    If you have read the feature article on "fertilizing a planted aquarium", you’ll know that aquatic plants require different nutrients. Next to light and carbon (via CO2 system), so-called micro- and macronutrients are in demand. These can be very well supplied via substrate fertilization.


    Among the micronutrients are the important trace elements for the plants. These include above all iron, but also manganese, boron, zinc and other metals in very small quantities. Deficiency symptoms of trace elements and iron in particular can be detected quite easily. The aquatic plant then often shows white shoot tips (more info on that topic can be found here). Especially if only certain plants have deficiency symptoms, the problem can be well remedied by a specific soil composting. The following products are soil fertilizers, which primarily contain micronutrients:

    • Seachem Flourish Tabs: Contains all ingredients of liquid fertilizer Flourish in dry tablet form.
    • JBL The 7 balls: Classic fertilizer ball in solid form.
    • Borneo Wild RED B: Quickly-dissolving fertilizer tabs. Can be placed optimally with the Flowgrow Injector.
    • ADA Multi Bottom: Slow-dissolving fertilizer sticks. Available in two sizes.
    • ADA Iron Bottom: Fertilizer sticks enriched with iron, that release their nutrients very slowly and steadily. Available in two sizes.
    • Easy Life Rootsticks: clay sticks with high iron content.
    • Dennerle PowerTabs: Rich in trace elements such as iron and manganese, but also magnesium as a macronutrient.


    The macronutrients include the elements nitrogen, phosphorus and potassium, which are summarized by the abbreviation NPK. These substances are needed by plants in larger quantities. Here, too, deficits can be identified by certain symptoms (see here). The following substrate fertilizers contain primarily macronutrients:

    • AQUARIO Neo plants tab: Tabs with important macronutrients nitrogen, phosphorus and potassium, but also magnesium and boron.
    • Tropica nutrition capsules: Capsules containing both micronutrients (iron, trace elements) and macronutrients (nitrogen, phosphorus).
    • Placement of substrate fertilizers

      Similar to the planting of single stems of aquatic plants, the introduction of soil fertilizers in the form of capsules, sticks or balls, goes much easier when using tweezers. With this tool, the products can be stuck much deeper into the ground than you could using just your fingers. In addition, no substrate has to be "shoveled" aside for this. During the placement, attention should be paid to the range of the respective fertilizer.

      Aqua Rebell - Injector - 36 cm

      Even more convenient are the so-called injectors for inserting sticks or capsules. It is important to make sure that the injector fits the particular shape of the fertilizer product. The Aqua Rebell Injector is compatible with the Borneo Wild capsules, the ADA Bottom Release with the corresponding ADA sticks..

      Liquid fertilizers are also suitable for supplying water plants with nutrients via the ground. In order to strengthen the vitality of caring plants, it is possible to use a syringe to introduce a little liquid fertilizer into the soil directly near the roots. In this case, the fertilizer should preferably have no contact with the head of water, so the syringe must be inserted correspondingly deep into the ground. A practical tool for the introduction of liquid fertilizer into the ground is provided by the manufacturer ADA with the Green Drop. This dosing aid consists of a feed nozzle and a small fertilizer reservoir made of glass, which can be permanently installed in the aquarium with the enclosed hoses and suction cups.

      ADA - Green Drop

      Already when setting up the aquarium you can directly provide the soil with suitable nutrients for the aquatic plants. Many manufacturers, such as ADA, Dennerle or JBL, offer a coordinated basic soil system, with the help of which one can optimally supply the aquarium plants via their roots right from the start. In some systems a kind of long-term depot fertilzer is used under the cover layer of the substrate. This material often consists of coarser lava scraps or pumice, in order to obtain good water circulation even in deeper zones. This improves nutrient transport and oxygenation. Often this fertilizing layer is further enriched with nutrients using certain pulverized additives, or useful soil bacteria or activated carbon are added to stabilize the microbiology in the substrate and ensure clearer water. If you want to know more about this topic, we recommend the article "building the substrate" from our Aquascaping Wiki.

      soil additives