A bracket system holds a filter(s) in quick-attach and quick-release fashion. Brackets are combined in modular fashion, with conduit between the brackets, to create a "bank" of filters easily changed in number, arrangement, and flow scheme. Top brackets and bottom brackets capture/support the top end and bottom end of a filter, respectively, and filter inlet and outlet ports preferably slide onto and off of cooperating tubes/ports in the bracket modules without tools or threaded connections. A retainer may pivot on and off of its respective filter, holding the filter in place and releasing the filter, respectively. After pivoting the retainer up from the filter, the filter may be lifted up off of its respective bottom module, so that the filter is substantially vertically and pivotally removable from the bracket system. A keyed system may ensure that only the appropriate filter fits into the appropriate filter holder, wherein the keyed system includes key protrusions and cooperating key recesses on the mating surfaces that form a fluid connection between the filter and the filter holder. Sets of holders and filters may be provided wherein each set has key structure at different radial locations on the members, so that filters from a particular set cannot be used with any other set's holder. A universally-keyed filter may also be supplied that has key structure that fits with and cooperates with more than one of the differently-keyed filter holders so that the universally-keyed filter may be used with the various sets' holders.