overflow question

[sphelps]

the main reason a Herbie flows more is head pressure, a standard durso or other standpipe operates at essentially zero head pressure while a Herbie has head pressure equal to the height of the overflow.

Out of curiosity why not share the model number of that pump?

Also when you branch of a line you don't look at it as a single system, for example, ignoring pipe friction, if you have two lines going up 8' you only have 8' of head pressure not 16'. So with your system you haven't analyzed it properly, you have less head pressure than you think.