Even if it looks clean, the mesh and sponge are not what's cleaning the water. There's probably a "gravel" inside the cartridge right? That's what's doing the filtering of the dangerous chemicals and such. The mesh is pprobably only there to keep the gravel clean of debris. Those kinds of cartridges need to be replaced every month.
Or, I bet the sponge is holding your good bacteria for you? Cuz if it is, you don't wanna replace that.
Last edited by ZanZan; 06-01-2009 at 03:42 PM.