OK, This thread is really cool.
I've been running a very similar setup for about a month now and it seems to be working great.
I have 2 Tom's aqualifters, and I bought 2 cheepo digital timers from Wally world ($8 and change each.)
You'll see I drilled out the caps and inserted check valves to prevent the vacuum that I see you guys were talking about.
Here's a couple pics of my setup.
