Foam cylinders for bass absorption

[xyrium]

Hello All,

I was thinking of buying some open cell foam cylinders that are about 10" in diameter, and 42" high, for use in corners to eliminate standing waves in my living room. Has anyone used these or suggest that this would be a decent idea? Do the cylinders need to be much higher than the top of the speakers?

Also, should the foam be soft, or firm for this type of usage? I pressed on my Sonex Jrs. and they seem pretty firm.

Thanks!
Paul