diverter valve

[Bergovoy]

I amusing a diverter valve to divert some of the water flow from my return pump back to teh sump because it is overflowing my tank, the drain / overflow can not keep up with the flow

I have a 180 gallon tank witha trapazoidal overflow with a 1-1/2 inch drain line and two one inch return lines in the overflow

I am using the mag 24, (oversized I know, but want to use it througha manifold to supply water to the chiller, the calc reactor and maybe the skimmer).

The diverter valve I have is from pondmaster

http://www.pondmasterstore.com/home/pm1/page_127_23/pondmaster_diverter_valve__24003600_gph.htm

The question I have is that the valve has a 1 inch inlet and outlet, threaded, and the diverter is a three quarter threaded outlet.

The three quarter outlet though will not seal on a standard three quarter female threaded to slip bushing adapter.

The adapter just screws all the way to the bottom and makes no seal. So it obviously leaks water?

Is there a different fitting or adapter I am supposed to use?

Is that fitting for a hose end, that has a rubber ring gasket?

Anyone useing this or have any otehr suggestion.

Thanks

Obviuosly this is the last thing I need to nail down to fill up my tank.

I am anxious to get this out of the way, but the back will not let me back down there to goof around. I ahve one more shot at going under the tank and fixing what it is and then the back is going to call it quits for a while...

So, please help
Thank

Bill