Devices and methods associated with these devices for significantly improving the efficiency of an existing or new filter having a granular media filter bed. The methods and devices are designed to increase the height and hence overall volume of the filter bed to allow for longer filtration runs between washing or cleaning cycles of the granular media filter bed. One embodiment includes a multi-wash trough adapter that upon removal of an existing deep wash trough connects two shallow wash troughs or two shallow wash trough channels to an existing wash trough opening formed in a wall of a filter compartment. The shallow members have a height significantly less than the height of the existing deep wash trough, e.g., one third to one half of the height of the existing deep wash trough allowing the volume of the granular media filter bed to be significantly increased.