I don't get grain in my lines I have a triple filtering false bottom because my little 3gpm pumps would jam with grain...
They say they are reed switch activated but I do believe there is a cone type piston? That the fluid applies pressure to so it opens.
I saw the one you linked but those appear to monitor and control flow and I'm looking for a on off flow switch to allow current and cut current to my SSR powering my rims element
I'm sorry if you've already answered this, hell I may have already asked, can you give details on how exactly your filtering to protect the little tan pumps? You use them for everything right, whirlpool and mash?