I’m not the one to ask. My knowledge on the subject comes from a single hour-long colloquium I attended, a few years ago.
You’re right. I stand corrected on that one.
A Vortex.
The filter medium is Diatomaceous Earth, but the charcoal acts as a chemical and super-fines filter.
I wanted one of those so badly about 1970, but couldn’t afford it with a paper route. A few years ago, one was in an aquarium that I bought at a thrift shop. The motor packed it in, I replaced it, it packed in, and I run it with an external pump.
I used mine as a manual cleaner, with a wand (my under gravel filters were the main filter). I would prime the filter (always a task), suck up a bunch of DE, and then suck up the charcoal. The filter would make the water like crystal.
Well, you see Ricky, when a boy palm tree really likes a girl palm tree… 
Coir fibre’s made from that bit (I think we’re talking about the same bit anyway), used for making doormats, brushes and suchlike, and the shorter fibres and the rest can be compressed for easy transport then used as a low nutrient compost base.
Ets: not that you’d make that at home from your whole foods coconut, but on a larger scale that’s the major use.