sumps never have to be divided, but the reasons to do so are as follows:
1) constant water level in a part of the sump. This can be important depending on what equipment you run
2) stable environment in said part to allow for the cunstruction of a fuge.
3) bubble blocking baffles to keep your tank looking pretty.
but any sump is better than none, since at least you get the additional volume and get the mess out of your tank.
54g all-glass bowfront corner planted FW
Red tiger lilly, Rotala Indica, Sagittaria Subulata, Micro Sword, Cardinal Plant
Fluorite Black sand and gravel