75 gal corner overflow filtering problem

I have a 75 gal with corner overflow thats seems to have problems filtering the larger particles. I moved powerhead around and tried different sizes and just cant find the right water flow either to much for my corals or not enough the corals are happy with water flow as is and doesn't seem to effect water quality just bugs me and was wondering if there is any tricks to getting particles out thought about adding small canister filter just for that purpose I only have an 1" off the wall I got a rio 3100 return witch splits into 2 hoses in the tank and a sieo 820 on opposite side any suggustions would be nice I would post pic. but having trouble attaching it

 

I have a sponge over the inlet thats cleaned weekly

 

I willing to try anything thanks for the link