Knocking all the time loudly. I have a steel wall pool (8-shape, 7,25x4,6x1,2m), because you can hear the really loud. The noise is very annoying and is basically not reasonable also to neighbors. The cleaner always starts from the same way, never clean the entire pool, not even significant parts. Wherever he goes, he sucks, but that's just not enough. No matter how long you make the hose and how to adjust the weight, it's not as hinzukriegen that it works. Reversal was at least easily. I can not recommend the pool vacuum, because it did not work with me.
