You can see into the bottom of the 1200's, do not know what it is eating but the point being as to how long a filter will effectively work before maintenance is required.
I have 2x 1200 aquaone filters on my 550L Gold nugget which have not been touched for over 6 months without any probs. I also have another aquaone which a baby guppy got into over 6 months ago and it is a full grown male still inside the filter.
I use filter wool and get my arms wet, it works way better than the magnetic ones which in my experience pick up small particles that scratch the glass.