The substrate of an aquarium refers to the material used on the tank bottom. It can affect water chemistry, filtration, and the well-being of the aquarium's inhabitants, and is also an important part of the aquarium's aesthetic appeal. The appropriate substrate depends on the type of aquarium; the most important parameter is whether the aquarium contains fresh water or saltwater. For other uses, see Aquarium (disambiguation). ... For the village on the Isle of Wight, see Freshwater, Isle of Wight. ... Sea water is water from a sea or ocean. ...

Substrates for freshwater aquaria

For freshwater aquaria, gravel is the most common substrate. Gravel sold specifically for use in aquaria is chemically inert. It may be naturally colored or dyed, and may have a polymer seal to ensure it does not affect water chemistry. For the village on the Isle of Wight, see Freshwater, Isle of Wight. ...

Types of substrates for freshwater include the following:

• Gravel. Aquarium gravel can be as coarse as pea-sized or as fine as 1–2 mm. It is commonly composed of quartz or other lime-free minerals. ^[1][2]
• Crushed coral skeletons or other seashells. Because calcium carbonate, the primary component of shells, increases water hardness, it is used most often for particularly for hard water species, such as those for African Rift Lake cichlids. Calcium carbonate substrates are poorly suited to aquaria housing most other freshwater aquarium fish, particularly river species, which are adapted to soft water. ^[2]
• Peat, or decomposed plant matter. Peat is used most commonly in soft water or blackwater river systems, such as those mimicking the Amazon River basin. In addition to being soft in texture and therefore suitable for demersal (bottom-dwelling) species such as Corydoras catfish, peat is reported to have a number of other beneficial functions in freshwater aquaria. It softens water by acting as an ion exchanger, it contains substances good for plants and for the reproductive health of fishes, and can even prevent algae growth and kill microorganisms. Peat often stains the water yellow or brown due to the leaching of tannins. ^[2]
• Sand. This is often recommended for use with certain species, such as the river stingrays of family Pomatotrygonidae, which bury themselves in the fine substrate. However, these species can be successfully kept with coarser substrates as well.

In some aquaria, different substrates are used in different parts of the tank. For example, peat can be used in one corner, while gravel in another portion allows rooted plants. ^[2] A millimetre (American spelling: millimeter), symbol mm is an SI unit of length that is equal to one thousandth of a metre. ... Lime is a general term for various naturally occurring minerals and materials derived from them in which carbonates, oxides and hydroxides of calcium predominate. ... Calcium carbonate is a chemical compound, with chemical formula CaCO3. ... Hard water is water that has a high mineral content (water with a low mineral content being known as soft water). ... Genera Apistogramma - Dwarf Cichlids Astronotus (Oscars) Boulengerochromis Cichlasoma - American Ciclids Crenicichla Pterophyllum - Freshwater Angelfish Symphysodon - Discus Teleogramma Tilapia Cichlids are a family of perciform fishes. ... Peat in Lewis, Scotland Peat is an accumulation of partially decayed vegetation matter. ... This article is unconnected to the various rivers named Blackwater: see Blackwater River (note capitalization) Blackwater rivers are rivers with waters colored like clear tea to coffee. ... A satellite image of the mouth of the Amazon River, looking south The Amazon River (occasionally River Amazon; Spanish: Río Amazonas, Portuguese: Rio Amazonas) of South America is one of the two longest rivers on Earth, the other being the Nile in Africa. ... Common Species Corydoras aeneus Corydoras metae Corydoras paleatus Corydoras panda Corydoras Sterbai Corydoras trilineatus Members of the South American Corydoras genus are popular freshwater aquarium catfish, and are commonly referred to as cory catfish or simply corys. ... Ion exchange is a process in which ions are exchanged between a solution and an ion exchanger, an insoluble solid or gel. ... Tannins are astringent, bitter-tasting plant polyphenols that bind and precipitate proteins. ...

Substrates for saltwater aquaria

For saltwater aquaria, coral gravel and coral sand are most common. Composed primarily of calcium carbonate, coral skeletons have a buffering effect on the water's pH. They also contribute calcium, needed by some invertebrates, to the water. Sea water is water from a sea or ocean. ... Buffer solutions are solutions which resist change in hydronium ion concentration (and consequent pH) upon addition of small amounts of acid or base, or upon dilution. ... The correct title of this article is pH. The initial letter is capitalized due to technical restrictions. ...

In a reef aquarium, the substrate can be an important part of managing the water chemistry. Calcium carbonate substrates such as those made from coral or oolitic aragonite are commonly used; when these minerals, insoluble in water, are dissolved by acid secretions, they release calcium and strontium, both of which are important to invertebrates such as stony corals. A reef tank or reef aquarium is considered to be one of the most difficult aquarium setups to create and maintain. ... Oolites are sedimentary rocks composed of ooids, which is a spherical grain composed of concentric layers. ... Aragonite Aragonite is a polymorph of the mineral calcite, both having the chemical composition CaCO3. ... General Name, Symbol, Number calcium, Ca, 20 Chemical series alkaline earth metals Group, Period, Block 2, 4, s Appearance silvery white Atomic mass 40. ... General Name, Symbol, Number strontium, Sr, 38 Chemical series alkaline earth metals Group, Period, Block 2, 5, s Appearance silvery white metallic Atomic mass 87. ...

Coral sand is considered the best substrate for a reef aquarium. At a depth of about 2.5 cm (1 in), it allows anoxic zones to form and host anaerobic bacteria which in turn denitrify the water, that is, convert nitrate to nitrogen gas. Animals such as sleeper gobies and some invertebrates such as turbo snails are useful to stir the sand. The metre, or meter (symbol: m) is the SI base unit of length. ... Mid-19th century tool for converting between different standards of the inch An inch is an Imperial and U.S. customary unit of length. ... An anaerobic organism or anaerobe is any organism that does not require oxygen for growth. ... In inorganic chemistry, a nitrate is a salt of nitric acid. ... General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless Atomic mass 14. ... Genera ~35, see text The Eleotridae are a family of fish found predominately in the found in the tropical Indo-Pacific. ... The name snail applies to most members of the molluscan class Gastropoda that have coiled shells. ...

Aquaria with marine invertebrates often incorporate live rock, which can be considered part of the substrate. Made of calcium carbonate, it has the same effects on water chemistry as coral gravel and sand. It is riddled with small holes and cavities which allow anoxic zones to form.^[3] Live rock is rock taken from the ocean which is usually encrusted with Coralline and inhabited by marine organisms. ...

See also: Biogeochemical cycle

In ecology, a biogeochemical cycle is a circuit where a nutrient moves back and forth between both biotic and abiotic components of ecosystems. ...

Substrates for specialty tanks

In planted tanks, fine gravel (1–2 mm) is often used. Coarser substrates allow debris to settle within the gaps between grains, which is particularly difficult to clean in a planted aquarium. Finer substrates such as sand are not well-aerated enough for plant roots. The substrate for plants should be at least 5 cm (2 in) deep. Sloping the gravel so it is most shallow in front accomodates larger plants with correspondingly larger root systems in the back.^[2] This article is being considered for deletion in accordance with Wikipedias deletion policy. ... Mid-19th century tool for converting between different standards of the inch An inch is an Imperial and U.S. customary unit of length. ...

In breeding tanks for egg-scattering species, a layer of marbles is sometimes used as a substrate, allowing the eggs to fall into the gaps between the marbles where the parents cannot eat them.^[4]

Quarantine tanks (sometimes called hospital tanks) often use no substrate at all. This assists in keeping the aquarium as clean as possible. ^[1]

Biological filtration via substrate

Beneficial bacteria colonize all aquarium surfaces that are exposed to aerated water. Because the numerous particles have a high surface area, substrates are often employed in biological filtration.

In an undergravel filter, substrate (most commonly gravel or crushed coral) is placed on top of a grate containing one or more uplift tubes. Water is caused pumped up the tubes using either an air pump or small water pump, forcing flow through the substrate and aerating the entire gravel bed. Beneficial bacteria colonize the gravel bed and provide biological filtration. Undergravel filters are most often used in small aquaria, although they can be used in larger systems.

Undergravel filters are not effective if the substrate bed is uneven. In an uneven gravel bed, water will flow only through the thin portions of the bed, leaving the more heavily covered areas to become anoxic. Because of this, animals that dig, such as cichlids, are best kept in an aquarium using some other type of filtration.

Even without an undergravel filter, some nitrifying bacteria are present on the surface of the substrate.

References

1. ^ ^a b Substrate Materials. The Tropical Tank. URL accessed on 2006-05-02.
2. ^ ^{a b c d e} Scheurmann, Ines (1985). Natural Aquarium Handbook, The, (trans. for Barron's Educational Series, Hauppauge, New York: 2000), Munich, Germany: Gräfe & Unzer GmbH.
3. ^ Delbeek, J. Charles; Julian Sprung (1994). Reef Aquarium, The, Volume 1. Coconut Grove, Florida: Ricordea Publishing.
4. ^ S. Russell. Breeding Zebrafish. (Chapter 2) The Zebrafish Book. URL accessed on 2006-05-02.