EZ-FLO EZ025-HC 23 gal High Capacity Fertilizing System The High Capacity version of our Main Line Systems includes a proprietary fill system allowing the tanks to double their water-soluble capacity. With this filling system, there is no need to remove the proportioning cap to add products. Additionally, the High Capacity models feature a larger drain valve, an automatic air vent valve, and a schedule 80 PVC body for added protection and durability. These units are constructed of heavy-walled, UV-Resistant PVC and have no moving parts, making them very reliable, dependable, and maintenance-free.