Culligan FVK-100 Flush Valve Kit for Easy Change Filter, Grey Use with IC-750 (SKU No. 4201661) and IC-1000 (Ace No. 4194346) Easy Change Filters The Culligan FVK-100 inline water filter flush kit is used to remove carbon fines after filter installation. The Culligan FVK-100 inline water filter flush kit can be used for any inline water filtration system with 1/4 inch tubing.