I wonder if you could chain two timers, picking their periods and durations appropriately to get a much longer combined period with the correct duration.
Well, you could use 2 timers with the same period, if they are accurate.
You would plug in timer 1, so that its output (output 1) is on. You would set timer 2 so that output 2 would turn on as soon as timer 2 receives power. When there are only 30 seconds left in timer 1's on cycle, you would plug timer 2 into a separate outlet.
Since they are synced, but only overlap by 30 seconds, they will only both be on for 30 seconds. You would then need some kind of AND that would only turn on the pump if output 2 and output 1 are both on.
