A composite filter aid comprising: diatomaceous earth, natural glass which is perlite, and a precipitated silica binder which is sodium silicate and wherein the ratio of the diatomaceous earth to the natural glass ranges from 1:3 to 3:1 by weight, wherein the filter aid has a permeability ranging from 1.97 x 10 -12 m 2 to 1.97 x 10 -11 m 2 (2 to 20 darcys) and wherein the diatomaceous earth comprises at least one of calcined diatomaceous earth and flux calcined diatomaceous earth and the composite filter aid has a d10 ranging from 10 to 30 μm (microns), a d50 ranging from 30 to 70 μm (microns) and a d90 ranging from 80 to 120 μm (microns), wherein d10 is the value at which 10% by weight of the particles have an equivalent spherical diameter (esd) less than that d10 value, wherein d50 is the value at which 50% by weight of the particles have an equivalent spherical diameter (esd) less than that d50 value, wherein d90 is the value at which 90% by weight of the particles have an equivalent spherical diameter (esd) less than that d90 value and d10, d50 and d90 are measured using a Leeds and Northrup Microtrac X100 laser particle size analyzer, further wherein the filter aid has a wet density ranging from 160 to 256 kg/m 3 (10 to 16 lbs/ft 3) and the wet density is measured by placing a weighed sample in a calibrated centrifuge tube to which deionized water is added, the sample is shaken until all of the sample is wetted and no powder remains, the tube is centrifuged for 5 minutes at 2500 rpm on a centrifuge equipped with a swinging bucket rotor, following centrifugation the volume of the settled matter is measured and the wet density calculated by dividing the sample weight by the measured volume. diatomaceous earth, natural glass which is perlite, and a precipitated silica binder which is sodium silicate and wherein the ratio of the diatomaceous earth to the natural glass ranges from 1:3 to 3:1 by weight, wherein the filter aid has a permeability ranging from 1.97 x 10 -12 m 2 to 1.97 x 10 -11 m 2 (2 to 20 darcys) and wherein the diatomaceous earth comprises at least one of calcined diatomaceous earth and flux calcined diatomaceous earth and the composite filter aid has a d10 ranging from 10 to 30 μm (microns), a d50 ranging from 30 to 70 μm (microns) and a d90 ranging from 80 to 120 μm (microns), wherein d10 is the value at which 10% by weight of the particles have an equivalent spherical diameter (esd) less than that d10 value, wherein d50 is the value at which 50% by weight of the particles have an equivalent spherical diameter (esd) less than that d50 value, wherein d90 is the value at which 90% by weight of the particles have an equivalent spherical diameter (esd) less than that d90 value and d10, d50 and d90 are measured using a Leeds and Northrup Microtrac X100 laser particle size analyzer, further wherein the filter aid has a wet density ranging from 160 to 256 kg/m 3 (10 to 16 lbs/ft 3) and the wet density is measured by placing a weighed sample in a calibrated centrifuge tube to which deionized water is added, the sample is shaken until all of the sample is wetted and no powder remains, the tube is centrifuged for 5 minutes at 2500 rpm on a centrifuge equipped with a swinging bucket rotor, following centrifugation the volume of the settled matter is measured and the wet density calculated by dividing the sample weight by the measured volume.