A google search yielded the pdf of an invention which can do this very thing. Here's what I was looking for:
The present invention is particularly applicable to the
removal of an aluminum hydroxide precipitate from a
potasssium hydroxide electrolyte by agglomerating said
precipitate onto the surface of a cartridge filter, remov-
ing said agglomerated particles from the surface of said
cartridge filter, and allowing said agglomerated parti-
cles to settle in said electrolyte. The average particle
size of the aluminum hydroxide particles which precipi-
tate from a potassium hydroxide electrolyte is in the
range of about 0.5 to about 20 microns. Such particles
settle in the electrolyte too slowly for efficient separa-
tion by settling. By agglomerating the particles
using a cartridge filter, the rate of settling is increased to
the extent that separation by settling can be used.
This invention appears to have been granted in 1991. I presume that it has resulted in products that one can easily obtain and put to use in a closed loop system.