topz, my pump runs constant.

So, an SLO works like a non-firing bell siphon...you have your stand pipe, cut to the height you want the water level at. Same as if it was a continuous flow raft system, then you add a non-pressuring bell or a pipe with notches on the bottom, over top of the stand pipe.

I guess I've been using an SLO on my new duckweed setup...works great, it only pulls water from the bottom of the tank as the duckweed floats on top.