Nige,
That's great, I was about to try and make a start, never having water washed any bio!
I've tried to split the page into three sections with a diagram for each (although I know two or more can be combined). Is your text specific to bubble washing or does it cover all methods?
I did a little research and found some people in the US wash with a mixer paddle in the tank. Do you think that's worth including, even if only to steer people away from the design as it seems prone to creating emulsions?