is there a trick to matching return flow on a herbie?

[rjengen]

A gate valve is the only way if you ask me. I attempted my Herbi with a ball valve, and it worked...ish, then I tried a knife valve, which worked, but was very tempermental...Finally sprang for a gate valve, and I've never looked back. What I did was have my gate closed and that filled the tank up and had the water moving through the emergency overflow. I then slowly in 1/4 increments started opening the gate valve. Once I got the water level close to where I wanted it in the overflow, I would start tweeking it in 1/8 of a turn increments. It might take a day to get it fully adjusted and tweeked, but you should be good once it's set. I have noticed once my filter sock started to get clogged, my overflow will raise, which is a good indication that it's time to switch socks. Hope that helps