i use a small bottle karcher on my karcher.
had an AB one, worked like a treat a few times, before the brass fitting got so tight.
had a replacement and it was worst.
was told to drill it, but paying so much for an item having to make it fit was very poor.
hence my use of the small karcher bottle. doesn't foam as much, but it does the job, for an initial stage, to clean off any top layer dirty