[untamed]

Originally Posted by GreenSpottedPuffer

Ok that makes sense. So for water testing, I should start with the gate valve open completely and fire up the return pump and then start to close off the valve? Seems like a pretty good chance for a bit of an overflow until you get it dial in perfectly. How long did it take for you to set it? Would you also start by approximating how much flow you want to go to the refugium before you turn on the return pump? Does that make any sense? I guess I am trying to figure out how to get both herbies working together. Im guessing just a lot of adjusting until it works.

I have 4 separate Herbie overflows in my system and they are all inter-related. Any change to any of them affects the others.

Yes, start up with the gate valve wide open. It will be noisy and the water level in the overflow box will be right on the bottom. That will prove to you that you've designed with excess capacity.

Next test: Shut the gate valve 100% closed. This will test your emergency overflow. This is the test that will make you nervous as the overflow water level rises up to that emergency level. You need to know for sure that the emergency overflow can take ALL the volume. Be ready to stop the return pump, or open that gate valve fast....just in case. (and make sure that the emergency overflow actually has pipe connected to it!!!!)

When you go to fine tune things, you'll find that small changes to the gate valve make a difference. It also takes a while for the system to equalize after a change, so adjust slowly.