I am actualy planning this for my next tank.. I have been looking into it for about 4 years now. you need two valves, one pump and a bunch of plumbing to do it right. this also includes drilling both ends of the tank with several holes.
what I am planning is about 6- 1" bulkheads on each end which combine into a manafold on each end. then 2" line splitting to two actuated valves one on the suction side and one on the discharge side of the pump.
with this set up you will actualy get complete lamaner flow across the whole tank so when in operation the bulkheads on one end are the discharge and the ones on the other end are the suction, when the ballvalves change this suction and discharge change ends.
this is the ball valve if you notice the one configeration has no "off" so during change over water flowes through both outlets.
http://www.haywardflowcontrol.com/pd...Way_Valves.pdf
here is the actuator
http://smsnet1.smsmktg.com/~hayward/...s_Actuator.pdf
the only other thing to do would be to come up with a controler that would alternat power on a timed basis to open one as it closes the other, then after a set time reverse the process. this could be done with an adruno based micro processor or what ever.
Steve
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