Well; I've got three of these now! In most of them I have the poly pads that came with it, with some pond media, similar to
this that my mum had spare from doing her pond filter; it's not probably not ideal but I haven't got around to replacing it with something more efficient!
I find it works better than sponges because the poly pads get the 'bit's and can be washed quite 'aggressively' (I do one each filter clean under the tap!) and the biomedia stays pretty clean; I don't wash that at all; it just gets dumped in a bucket of tank water while I do the pads.
I have had external filters with sponges before, and I found you had to wash them quite roughly to stop them clogging up and I always felt I must be losing a lot of bacteria. It was a long time ago, before readily available test kits, so whether I ever had mini-cycles because of it, I couldn't say. My fish were always fine, so it could just have been my paranoia!
Oh, yes; forgot the set-up
Bottom tray; poly pad and pond media
next; poly pad and pond media
next; poly pad and pond media
top; poly pad, ceramic rings and spare sponges
The pond media is plastic, and floats, which can be annoying when you're trying to get the top of the filter back on, that's the only reason the ceramic rings are at the top!
I personally don't feel it makes all that much difference what order things are in.
if they dont i do apologise! the only thing i can think of other than that is ringing sunsun up and asking,
