was it Yama Mountain that offered no-see-um mesh scraps cut into filter sized bags a little smaller than a coffee filter? IIRC, you could get ten for as little as $3.50. I think they were offered for straining your dinner grey water so you could trash the food bits and poor the water out on the ground. I think they'd work well as a prefilter too, and probably last many uses. I couldn't find the link, but if anyone else can I'd like to bookmark it.