Eheim Classic 350 vs Fluval 307: The Full Breakdown If you’re shopping for a canister filter in the mid-range bracket, chances are you’ve landed on the same two names everyone does — the Eheim Classic 350 and the Fluval 307. Both sit in that sweet spot for tanks around 50 to 90 gallons, both have loyal followings, and both will do a solid job keeping your water clean. But they’re surprisingly different filters once you look past the spec sheets. The Eheim Classic 350 is the no-frills workhorse that’s been running quietly in fishrooms for decades. The Fluval 307 is the modern, feature-packed option that makes maintenance as painless as possible. Choosing between them really comes down to what you value more: proven simplicity or thoughtful convenience. ...