reef breeder pico vs tunze chic which is recommended also which tunze 8850 or 8831 area of fuge is 12x12 and it will be around 9 in deep could go deeper
Either one should work fine. I use the kessil H80 myself footage below). Your other concern should be preventing light spreading into other sump chambers (unless this is a standalone tank) to prevent unwanted algae growth outside the fuge.
A lot of folks don't like economy lighting, but Finnex makes a decent refugium light(aquacave), $85 gets you 20 watts (kessill h80 is 15 w) would fit great on a 12 x 12 fuge. Its blurple colored, no control available, needs a timer. 2 banks of light that can be independently turn on/off. I use the BN-LINK timer (BND-60/U58S) $17 dollars and has battery back up for programs (amazon)