Airstone

An airstone, also called an aquarium bubbler, is a piece of aquarium furniture, traditionally a piece of limewood or porous stone, whose purpose is to gradually diffuse air 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 increasingly being made from bonded glass beads and synthetic products like fiberglass.

There is some controversy as to the efficiency of airstones versus the conventional powerhead system when used in uplift tubes as part of an under-gravel filter.

The original method of protein skimming, running pressurized air through a diffuser to produce large quantities of micro bubbles, remains a viable, effective, and economic choice, although newer technologies may require lower maintenance.

Air stone protein skimmers may be constructed as a DIY project from PVC pipes and fittings at low cost [1] [2] Archived 2009-01-23 at the Wayback Machine and with varying degrees of complexity [3].