Herbie overflow tuning

[Myka]

I don't see anything odd about the plumbing setup. I think you're either trying to get it too perfect (ie trying to have no water going down emergency drain) or you're over compensating each direction. Fwiw, I always keep a small trickle going through my emergency drain as well. If the main line is starting to get clogged up and there is significant water going down the emergency line it makes lots of noise (good alert). Getting it "perfect" is terribly frustrating. My ATO pushes a bit of extra water down the emergency drain while it is running, but this is definitely not a concern.