Yes, for a drilled tank, you should either have a baffle (what ccCapt is describing) that controls the water level, or use a stand pipe attached to the bulkhead. This prevents the tank from draining down with a power out.
Some tanks are drilled at the side so the bulkhead is placed higher, to control the water level. Personally, I still think you should still use a standpipe in that setup. this allows you to change the water level, and also quieten the water noise. <And if you use a stand pipe, it makes no difference if the bulkhead is at the bottom, top or middle! >
80 gal FW with 30 gal DIY wet/dry/sump.
9 fancy golds, 1 hillstream loaches, 1 rubber-lip pleco (C. thomasi), 3 SAEs, small school of white cloud minnows, planted.