An airstone is a piece of aquarium furniture, traditionally a piece of limewood or porous stone, whose purpose is to gradually diffuse oxygen into the tank, eliminating the noise and large bubbles of conventional air filtration systems, and providing other benefits to the health of the fish. Airstones are sold in a very wide variety of shapess, sizes, and levels of coarseness--from extremely rough, producing larger (though still typically unnoticeable) bubbles and letting in more oxygen--to very fine, producing minuscule bubbles. Airstones are increasingly being made from bonded glass beads and synthetic products like fiberglass. Aquarium furniture refers to the various ornaments and functional items in an aquarium. ... General Name, Symbol, Number oxygen, O, 8 Chemical series nonmetals Group, Period, Block 16, 2, p Appearance colorless Atomic mass 15. ... Groups Conodonta Hyperoartia Petromyzontidae (lampreys) Pteraspidomorphi (early jawless fish) Thelodonti Anaspida Cephalaspidomorphi (early jawless fish) Galeaspida Pituriaspida Osteostraci Gnathostomata (jawed vertebrates) Placodermi Chondrichthyes (cartilaginous fish) Acanthodii Osteichthyes (bony fish) Actinopterygii (ray-finned fish) Sarcopterygii (lobe-finned fish) Actinistia (coelacanths) Dipnoi (lungfish) A fish is a poikilothermic (cold-blooded)* water-dwelling... The materials definition of a glass is a uniform amorphous solid material, usually produced when a suitably viscous molten material cools very rapidly, thereby not giving enough time for a regular crystal lattice to form. ... Generally, synthetic means pertaining to synthesis, i. ... Fiberglass or fibreglass is material made from extremely fine fibers of glass. ...

There is some controversy as to the efficiency of airstones versus the conventional powerhead system. Arguments can be made in favor of both systems, and both possess certain advantages and disadvantages. Among aquarists, the choice is very much a matter of personal preference, although the question is sometimes a shibboleth in Internet discussions. Aquarium is also the name of the Russian band, which is also spelled Akvarium A 335,000 gallon (1. ... Look up Shibboleth on Wiktionary, the free dictionary For the Internet2 research project, see Shibboleth (Internet2). ... Gaia Online, the largest English language forum-based community as of April 2005 — powered by a modified version of phpBB. An Internet forum is a web application which provides for discussion, often in conjunction with online communities. ...

External links

• http://www.marineandreef.com/shoppro/protein_skimmers_Airstone.html -- Website of an aquarium supplier
• http://www.thekrib.com/Plants/CO2/airstone.html -- Information on the airstone controversy