Product review (5 stars): Works well for me.
Works well for me. It lasts me for about three months until mineral deposits create a hard film on the top side. Once that happens, I invert it and use it until the other side hardens. Instructions say to replace at that point. I also clean the filter about every 3 weeks by soaking it in a mild bleach solution (about 10% Clorox) until all traces of dark material disappears.