I should also add that if i were to plumb a new tank, I would make sure that both overflows had their own totally separate plumbing. Right now my overflow plumbing runs meet in a t-union, then drop through a 3 way valve. If the valve is set to the right, water enters the skimmer chamber and flows through the whole sump. If the valve is set to the left, water drops out a pipe in the first part of the bubble trap, bypassing the skimmer, fuge, and water change chamber (3/4 of the sump), so that I can do semi-automated water changes in the water change chamber.
Because I know nothing about physics, I didn't realize that having the two pipe runs plumbed together in one outlet would make using a herbie basically impossible. Even though the gate valves for the herbies are right underneath the bulkheads, being plumbed together downstream makes them behave as one highly unstable system. I'd get the levels set just right in the overflow chambers, then if the return pump shut off, or if I sneezed too loudly in the next room, one of the overflow boxes would fill up to overflowing (often triggering the emergency overflow if that was the one that filled up), while the other would drain so much that it sounded like a water fall in my tank. This wreaked havoc on the auto-top off as the level in the return chamber would fluctuate over the course of the day, and sometimes led to so much fresh water being added that the salinity would fall a couple thousandths and the tank would be near overflowing.
Because of that I've had to ditch the herbies and go back to using a durso, which is noisy and produces so many micro-bubbles. If the filter socks start overflowing at all (with a durso, that happens every 24 hours), the U shape design of my sump takes the micro-bubbles right up to the display.
Moral of the story - to use herbies or a herbie style design in which flow from the tank in to the sump is restricted in some way, each drain needs to be plumbed from bulkhead to sump in isolation.
|