I have two planks in my tank controlled by a Profilux, and I think the way I have it set up is working very well. (I mostly got the second plank so I could have one on each side of the tank - when I only had one, the fish were all hanging around all day on that side of the tank.)
So you can get this done with one timer. I have one pair of timers controlling the plank feeding augers, and I use programmable logic to turn on their corresponding pumps, with a delay for them to run two minutes after the motor stops. That way you make sure that all the food makes it into the water column. Controlling the pump with programmable logic instead of a timer is cleaner, that way you don't have to deal with two timers every time you want to modify the feeding schedule.
I know some people keep their pumps running all the time, but I haven't found that necessary at all, and besides the waste of electricity you have to hear them all the time and it's wear and tear on the pumps.
I also have my powerheads set to turn off while the feeding pumps are running, so the food isn't blasted all over the tank.
And I also use the pumps for feeding frozen. I turn the pumps on using a button mounted over the tank that sends a digital signal to the profilux. When you push the button, the pumps come on for 5 minutes and the powerheads turn off. I think this is a great way to feed frozen - the whirlpool that the pump generates defrosts the food and dispenses the pieces of mysis or whatever into the water column. No more dealing with thawing frozen food - just pop the cubes into the plank tubes, press the button, and walk away.
The way this is all working is a little complicated, so I won't get into specifics here. But if you want to set up your planks this way then let me know and I'll give you the details.
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