I don't think so. The rock you have will be your primary biological filter. The mechanical filtration will remove particulate matter and such, but this needs to be cleaned on a regular basis or it could become more of a downfall than anything else IME. You might be better off keeping the filters empty & just using them for flow, but when you do your water changes and stir things up then incorporate the sponges, a filter sock etc to polish the water for a few hours. FWIW my reef tank has been set up for about 7 years now and I've never found the need to use a mechanical filter on a regular basis. Just as an example, I would much rather have any leftover food keep making revolutions throughout the system until something can utilize it as opposed to sitting in a filter sock or sponge for days on end rotting. GL.