[gregzz4]

Hey Dunc

I know you said this setup is fairly new, but could there be something in the drain ?

I have the same problem with my 'fuge from time to time. It'll climb to overflowing and I try to open it up enough to lower it. But then it just suddenly drops as if I opened it wide

I find the only way to reset it is to open it all the way to flush out whatevers in there and then I can reset it just fine. And it lasts for months after a flush

Another thing
Is your plumbing under water in the sump ? If not air in there will mess with your levels

Oh, btw, I haven't had to tune my setup since my build over 2 years ago (except if the pump strainer gets clogged), and I don't purposely run anything down the emerg