@aradke: you are right, that’s the command to change the water percentage.
A few weeks ago I posted a more complete list of HTTP GET commands on the website:
http://rayshobby.net/?page_id=730#httpget
(click on the PDF link). The commands to change option values (such as the water percentage) are kind of messy and obscure, but hopefully this document will help.
@grondo: the ‘cycle-and-soak’ program is an interesting idea. aradke’s suggestion should work (e.g. a single program for each ‘cycle-and-soak’ station with 20 minutes interval time and 10 minutes water time).