Remember overheads and canisters arent meant to establish "flow". Flow and filtration are two totally different things the only time they are the same is when someone has a closed loop system. Like the FX5 states "Filters 400 gallon" which is true, but it wont establish the needed flow for a 400 gallon. So remember when you use canisters and overhead you STILL need to establish flow with fan powerheads.