If you're wondering which of these robot vacuums has more suction power, the Roborock S8 MaxV Ultra wins by a significant margin. It delivers 10,000 Pa of suction power versus the Roomba j9+'s estimated 2,200 Pa. That's roughly 4.5 times more raw suction.
What Do Those Numbers Actually Mean?
Here's the reality: 10,000 Pa is massive for a robot vacuum. Most budget models hover around 2,000-3,000 Pa. The Roborock S8 MaxV Ultra is in a different league entirely.
iRobot doesn't officially publish Pa ratings for the Roomba j9+, preferring to highlight their "4-Stage Cleaning System" instead. Independent testers have measured it at around 2,200 Pa. That's solid, just not in the same ballpark as the Roborock.
Where You'll Actually Notice the Difference
On thick carpets: This is where the S8 MaxV Ultra shines. That extra suction pulls dirt and pet hair from deep within carpet fibers in one pass. The Roomba j9+ gets there eventually, but it often needs two or three passes to match the results.
On hard floors: Both do an excellent job. When debris sits on the surface rather than embedded in fibers, you don't need 10,000 Pa to pick it up.
With pet hair: If you have pets that shed heavily, the Roborock's stronger suction extracts embedded hair more effectively from carpets and upholstery.
The Roomba Has Smart Features Too
The j9+ compensates with intelligent software. iRobot's Dirt Detective technology automatically cranks up suction when it hits dirty spots. The vacuum figures out which areas need extra passes and adjusts accordingly. Less brute force, but smarter application of what it has.
The Verdict
Need to clean thick carpets or deal with serious pet hair? The Roborock S8 MaxV Ultra's 10,000 Pa suction is the better choice. Mostly hard floors with light cleaning needs? The Roomba j9+ will serve you well without the premium price tag.
