Screen size debate

Does nobody conclude that the "thicker" growth is acting as a particle filter ? When I grew my screen thin i.e. 7 or 8 days, the water contained within the mat was a dirty brown green, full of detrital particles. This situation changes, the longer the screen is left between cleaning. At 14 to 28 days, the water within the mat is crystal clear. This presumably means the detrital particles have been consumed by bacteria. However, there's a problem with this theory. In my G.H.O.S.T. Screen, the detrital particles settle quickly because its horizontal and seem to remain there for an extended period of time without significant breakdown. There is a difference between the algae growth however. The detritus on the waterfall screen is in direct contact with the algae (and bacterial assemblages), whereas the ditritus collected on the G.H.O.S.T. is away from most of the algae mass (which tends to accumulate near the surface) and the water passes under the algae mat.