Liberty lowpro

I just installed a Liberty LowPro41LP low profile sewage System in a basement remodel. It is also taking the vanity and the whirlpool tub. Lift is ~6', distance is ~ 8'. I finally got the tub hooked up and filled it. The toilet is not yet installed on the flange. The tub is raised 8" above the top of the tank.

When I drained the tub, the pump operated as to specs: it came on at 4" depth of water in the tank, but it couldn't keep up with the flow, so overflowed through the open flange. Will this remedy itself once I have the toilet installed? Doesn't seem right to me. The pump should be moving water at ~120 gpm, is there more than that coming through the 1-1/2" waste line?

Any other info you guys might need? My plumber is coming in to look at it, but thought I might get a jump on problem solving (and worrying!) Thanks

pump

The only way installing the toilet will remedy it, unless you find some other cause, is that the water will not be high enough to overflow the toilet, and the toilet seal should keep it from leaking out. But if this is going to be your normal situation, then you will not be able to flush the toilet while the tub is draining.

thanks HJ, that's kinda what I thought. How much water will come through the 1-1/2" drain from the tub? I can't imagine that it is 120 gpm is it? That's what the pump is rated to move at the height and distance it is from the sewer.