wrote in message
The CPR unit I'm talking about is a combination filter AND refugium,
with a little bit of a sump at the tank return for dosing, etc.

OK---I get it, its a particular model. Not ALL Aquafuges are filters?
I think you are talking about the Aquafuge MP.
here is a link. Let me know if this is the right model.
http://www.cpraquatic.com/products/afmp.html
It doesnt look like a HOB though---so it looks like it would still be an
underneath type of sump that I might not want to deal with. Is there a HOB
refugium that has the features you are mentioning?

thanks!