I have set my FX6 up using the coarse and medium sponges in the outer rings as per Pondguru advice. These sponges do get quite compressed to squeeze into position. I have noticed that some larger waste, bits of leaves etc, end up on top of the floss on top of the central section. Is it possible that these sponges, being compressed, cause a bit of a short circuit and I may be best reverting to the original outer sponges, or is this short circuiting not possible?