Hmmm...couldn't think of what else to call this subject :-?
I cleaned my filter today (all hang ons). I was one filter short. The whisper filter has 2 cartridges that are plastic, slip on white media that you fill with carbon. The other cartridges for the other filters have carbon in them (it was one of these I was short). Anyway, rather than only have the blue media on one side, I took one of the filters that were for the whisper filter (new) and used it. I didn't bother to put carbon in it. It didn't quite fit in the slot. So, I'm guessing this is ok????
Caper