Hi Arno,

thanks, very good ideas and descpription. 

Something to add. Olivier Beauté (Amel boat expert ond former SAV of Amel) instructed me so, and I do it with good success since over 4 years. 

Before starting the manual cleaning procedure I

1. empty the bilge with the manual pump 
2. take 2 tablets of small bags of cleaning substance for the DISH WASHER (makes no foam!!!) in the sink in the pantry, dilute it well in very hot water, 
3. drain it into the bilge, add a lot of hot water (even if the hot water tank is empty) by separately boiled water mixed with cold wtare to about 70 °C, and drain it until the bilge is completely full (disconntect the contacts for the electrical bilge pump before).
4. let it work for at least one, better more hours, it softens and cleans the heavy mug at the sides and bottom an everywhere in the bilge 
5. pump this cocktail :-) out with the manual bilge pump. 

I do this always after a 4-5 week sail, sometimes on half time also. 
The complete process (with the Kärcher) runs on my ship only once a year or even less due to this prevention of thick mug layers. 

Hope this is an additional idea to the perfect process you have described. 

Alexander, SY Oceanica I Amel 54#156