I got so excited over the price (read: I'm chea...ummm...frugal :mrgreen

that I forgot to mention how IMO undesirable these matted quilt battings are.
These mats are not thick so the detritus will quickly bypass the filter fibers and end up back into the water column. With the polyester fiber in loose form, I can pack them into at least 2" thickness. They are so effective at trapping particulate matters that in my Eheim 2113 where I stuff them to 5" thick, you can shine a flashlight onto the see-through canister and see the progression of particles traveling up the fibers over a period of several months; at which time, I replace with new fibers.
Good eyesight is not required either because the clean fibers will be colored WHITE until clogged with detritus/bacteria action.
