It is better than manual vacuuming when it comes to time and effect. I have found it isn't always better at cleaning certain kinds of dirt and debris. Just like you feel a pressure wave from a car when it drives by you, observing my robot indicates it puts out a small pressure wave as it moves across the bottom. I have observed debris with high surface area to weight ratio (a leaf) get pushed out of the way as the robot approaches it. Right now I have been vacuuming more manually because my daughter's dog gets a lot of fine lightweight mulch particles into the pool. I can run the robot for a cycle and then the fine dirt resettles on the bottom after it finishes. If I vacuum manually, I have to run the vacuum head slowly over the pool. If I move it fast, I see a cloud of dirt move away from the vacuum head. Yes, it is not algae as the water is clear, the FC levels are more than adequate and I have run the OCLT.