Hi and welcome to discus Jimmy .
It seems to me that you have diligently done your homework on discus before you take the plunge and you are ready to suceffully grow them out .
For filtration most of us use canister , Hob or sump filters .Sponge is good as a prefilter to your filter intake to keep your filter materials clean of dirt .
Good luck with your choice Jimmy and don't hesitate to ask anything about your future discus plans .