Red Sea ReefMat 250RedSea ReefMat 250 The ReefMat 250 is a plug & play, fully automated roller filter that keeps the aquarium water crystal clear, with a unique mat replacement system that allows you to switch rolls without having to remove the filter from the sump or even turn off the pumps. It includes a fail proof solid state level sensor and a smart drive unit that connects it to the ReefBeat ecosystem, controlling and monitoring the exact length of the used mat,