Sponges are much more restrictive, and if one clogs up enough, you could have flooding issues. You could cut the power to your return and shake the LR off as you remove it from the back chamber. Then siphon out the water in there, which may be enough to count for a water change. Not sure how much water they hold in those chambers. www.nano-reef.com and www.nanotuners.com are two good sites for info.