In forested and low-relief riverine habitats, nutrient concentrations in the water column, itself, tend to be poor, the bulk of the nutrient pool existing within the substrate composing the river bottom; these nutrients are present primarily as a result of the continuous deposition of mineral- and organic-rich sediment being carried from upstream and from run-off. Water chemistry in such riverine habitats tends to be slightly- to moderately-acidic, and generally low in concentrations of the elements that contribute to general hardness ("GH"). Plants endemic to these habitats, which constitute the majority of species commonly maintained in planted aquaria, obtain a considerable percentage of their nutrient requirements through their roots; it is therefore sensible to utilize a growth medium in planted aquaria that facilitates delivery of nutrients to the roots, themselves, as doing so encourages strong root growth and long-term plant health. Maintaining plants, fishes, and motile invertebrates (such as the various species of shrimp that are maintained in biotope aquaria and as algal grazers) endemic to these habitats in water chemistry conditions, specifically in terms of pH and mineral content, similar to those that they have evolved in is also sensible, and is likely to have a positive impact on their collective health. FlorinVolcanīt Rio Café-F is a natural volcanic ash that has been formed into particles resembling oblong beads. The beads, themselves, are firm yet pliable, and are sufficiently durable to retain their shape for one or more years, depending upon the specific water chemistry in the system (a tendency towards alkaline water causes the material to deteriorate more rapidly than when maintained in water with lower initial alkalinity). Rio Café-F gradually lowers GH and pH to create conditions conducive to long-term husbandry of plants, fishes, and invertebrates endemic to most rainforest streams, rivers, and pools.