Mogo,
My surges go once every minute or so. They're about 1-2 gallons each time in a 30 gallon tank. For a 140, you could probably make 2 5g buckets or one 10g tank as a surge. The frequency isn't really all that important, IMO. I've seen great coral growth in a tank that surges once every 10 minutes. The surge in that tank was amazing, though. It was about 10 feet higher than the tank, and about twice the water volume of the display. As long as you periodically wash all the polyps with a good blast of water, you should be OK.
HTH, Matt