Coast to coast overflow hampers wave?

[sphelps]

I don't think you need to be a professor to understand why coast to coast overflows and waves don't mesh well. Power heads are relatively small pumps but can generate waves by pulsing at a certain frequency that resonates at a natural frequency based on the tank dimensions, head pressure has nothing to do with it, however volume certainly does but not the issue here. This natural frequency is very sensitive, you'll notice that by changing the pulse interval slightly the wave will disappear, thus illustrating the sensitivity. An overflow box will disrupt the wave because every time water is pushed to one side a portion of the volume is absorbed by the overflow box so less volume bonces back as a result. Coast to coast or double overflows are the worst as they'll absorb the most volume as they are located on the far side on both sides of the tank and therefore the wave. Besides no overflow at all, center overflows are the best for generating waves so blocking off both sides of the coast to coast will produce a noticeably bigger wave.