Many filter feeders produce pseudo-faeces from selected particles that are filtered; pseudo-faeces does not pass the gut. Food intake can be limited by the filtering (acquisition) as well as the digestion (processing) rate. Its dynamics can be analysed in a straightforward way in the context of the Dynamic Energy Budget (DEB) theory using the closed hand-shaking protocol of Synthesizing Units. The model reveals how food intake depends on the relative size of the filtering and digestion machinery, which can be used to model differentated growth of these structures if allocation is linked to their relative workload. It turns out that non-digestible particles modify the apparent half-saturation coefficient, which makes that estimates for this coefficient can be used to quantify the mean silt load in a given habitat. © 2006 Elsevier B.V. All rights reserved.