from Wiktionary, Creative Commons Attribution/Share-Alike License.
- noun A piece of
aquarium furniture, traditionally limewoodor porous stone, whose purpose is to diffuse oxygengradually into the tank, eliminating the noise and large bubbles of conventional air filtration systems.
from Wiktionary, Creative Commons Attribution/Share-Alike License
The airstone is connected to an inexpensive air pump like they use outside of fish tanks.
I grow mine in water, with nutrients (fertilizer) added and an airstone in the water to oxygenate the roots.
* If an airstone is used, be sure it is acid resistant.