i would say it depends on 2 factors.
1. how high is your water level when the tank is running normally?
2. how high is your standing wave going to be?
i would say as long as you have 1/2" between the top of the tank and the top of the wave at its highest you should be fine. of course this is given that the the overflow does not get clogged with algae or coral growth
I recently switched to standing. I couldn't get back and forth working well without blowing my sand all over. I've got all of my pumps turned up higher than they were and the standing wave going. There MUST be more flow than there was, it's just hard to see without the sanding blowing all around.