On my filter on the intake tube, there is an adjustable intake valve towards the top that in varying degrees would bypass the intake at the bottom of the tube.
said this will vary the output flow of the water that doesn't.t make sense. It seems more like it is either to reduce the intake vacuum on the bottom intake or to simply have the option to pull water from higher up in the tank rather than all from the bottom. It's a penguin filter. Done of huge included docs mention it. What's is the general idea of the valve?