<p>A biological processing system includes a platform assembly for holding slides and a dispenser assembly with dispensers. The dispensers are sequentially positionable over specimen-bearing slides to enable dispensing of substances onto specimens. The dispensers include a filter device for filtering a processing substance such that a substantially precipitate free filtrate is applied to the specimens. The dispenser includes a filter device positioned at least partially in a reservoir chamber. The filter device includes anti-clogging features to maintain desired performance.</p>
