Yes, there are many external filters that will work on a tank that size;
Tetratec EX600, my personal perferance. Easy to work, reliable and quiet
Rena XP1. Solid, reliable when well maintained, easy-ish to work, accessing the seal for maintenance isn't the easiest task, but otherwise a great filter
Eheim 2026. Solid, quiet and reliable. Widely considered the best, but you have to put up the £££ for it...
Eheim classic 2213. Quiet and reliable, trickier than most to work though, with no self-primer
Personally, I'd avoid Fluvals, as IME they are noisy, un-reliable and more tricky than most to work on... AquaOne I'd also avoid, as while relable, quiet and easy to work, they no longer supply replacement parts, so when something need replacing, it's new filter time
All the best
Rabbut