Live rock in cannister filter
 

I have an eheim 2217 cannister filter in my FOWLR setup. It's currently holding some mechanical filter pads but I'm concerned about nitrate buildup (as I don't see myself being able to clean it often).

Would live rock be a good addition to the cannister? I have zero light in the cabinet where the cannister sits. Will the live rock be OK in a high flow zero light spot like a cannister filter? (or will it mostly die and cause more harm than good)

The LR would be your biological filtration and would be ok without light as long as O2 gets to it. BUT, as long as crud gets stopped and remains in the the filter, you will get an escalating level of DOC's and NO3....so you would still have to keep it maintained on a regular basis.