You probably have them both labeled as wavemaker A or both B. for alternating currents choose one A and one B. I prefer a surge like what you have described, and that is how I accomplished it. I labeled both wavemaker A which goes for 30 sec, and put wavemaker B on no pump, but it cycles for 10 sec so I get a little rebound before the next surge.
Hope this helps,
Mobi:lol2: