If you have been getting along fine without one than I don't see a need for one. However, If you want to take your aquarium to the next level, a controller would do that. You can customize it to your needs while adding piece of mind to your day. For example, programming wave makers with custom schedules to mimic natural ocean current patterns. Or, programming outlets to turn off or on for feeding or in the event of equipment failure. Live updates during emergencies or just checking the parameters while away from the tank for an extended period of time. Programming fail safes or convenient functions like turning a light on automatically when you open a cabinet door have never been easier. Personally, I use the Apex classic (Recently upgraded from the Jr.) and couldn't be happier. I could get by without one but the apex helps me with stability, redundancy, and piece of mind. Of course, there is always the risk of a controller failing, but I try to plan for situations like that and not rely to much on them.