I have noticed that my maxima isn't opening up all the way and last night I observed my lawnmower, literally, sitting on the mantle. Now, the interesting thing is that the clam could have cared less. It stayed open while the lawnmower sat there. Very funny to see. Not sure what is going on with my clam, but I suspect that my phosphate remover is iron based... I need to get some that is not ferric oxide if I can find it.