Has anybody any idea of the ratio at which to set the valves in my little sketch. r1 and r2 mean return pumps. Im not concern about the valves directly after the pumps as these im thinkin are really for being able to get the pump out and undertake maintenance and to 'tee-down' incase the return is greater then the capacity of the weir. I presume the left hand valves on each would be those requiring teeing down to allow a greater flow through the 'other leg' if you like. This is only an issue since you cant see whats comin out the end as its undrwater I asked a plumber and he said try running an air pump through but i cant acheive the same conditions as water with an air pump..... any ideas????