I wil be making mine soon, but here's a hint: You do not need a complicated 'controller brain' bucket with relays/float switches etc...
You could simply set up your timers to run for say "8 minutes fill," which depending no your pump, would fill it exactly to the level you need. Also, you could add a simple 'overflow' on a bucket in case something goes wrong to replace the float switches to prevent a mess.
I am thinking with timers and pumps you could set up everything without even needing a 'brain.'
These are gravity feed systems and take a few cycles to fill the buckets. I really don't know if you can safely do it w/o a controller bucket, but would like to hear about your results.