This is a standard revolution (albeit upside down)I dreamed this up to get more random flow with a 4 or 8 way, it indexes 8 times to 45 degree firings, each time the flow goes off it rises, or in your case would fall (by gravity) and part index, when pressure resumes it would be forced up and rotate again, you can see the 8 position cam in the pic below, you need a similar version to this that you might be able to build yourself.
You only need 4 position index, pump runs and water is sent to the right, pump turns off shuttle falls and partly indexes, 1 hour later pump turns on forcing spool up to the left output location and stays there till the pump turns off again.
If I get a moment I will sketch up a quick paint picture to make it clearer.
Paul