I agree, but so far the top five reasons not to have a closed loop system are:
1) cleaning the pump and the ocean motion device when debris get into the system.
2)The amount of holes you would have to drill through the back/sides of your tank. As a result, poosible leaks or breakage down the road and water on the floor depending on how low the holes are drilled of course.
3) The cost of the system itself $250.00 for a dart pump or =, oceans motions set-up $280.00+, and all the plumbing involved around $250.00 depending on how many gate valves and unions you use.
4) The general labor involved in planning and plumbing the systems itself.
5)After time the lines get clogged and flow is lost.
The Vortech controlable wave maker was recommended.
I myself am still on the fence.