well irreguardless of the kind of filter you have, the more water movement you have, the better particles will get filtered out. If the best filter in the world can only circulate water in part of the tank and theres some slower water areas, or dead space then the debris will settle there and your filter wont get it back until it gets kicked up again into the water column where it can pull it out. Not sure what kinda tank set up you have but obv you have some wood in there as you said. Shrimp dont eat algae off the glass....and theyre still gonna poo out w/e they eat in so they wont really "clean' then particles in the tank since shrimp poo is....well....particles lol. So i guess my advice would be to make sure you have good water movement so that whatever filter you do have can work as best it can. BNP and RCS are clean up crews but clean up crews are just clean up hiders really.