Click or scroll to zoom Tap or pinch to zoom ES O2 Cylinder Stone 1.75" by Elemental Solutions Sale $1.99 SKU 1 2 3 4 5 6 7 8 9 10+ Quantity Quantity Buy Now This Elemental Solutions® O2 Cylinder Stone accelerates oxygen replenishment and increases water circulation when used with a high-output air pump. The 1.75-inch O2 Cylinder Stone has a 2-inch diameter and is compatible with 3/16-inch-ID tubing.