Stuck in the Cistern

[Evolution13]

Okay, I've completed the control room puzzle, the weights are set, the levers are set, the pipes are set. After I completed the pipes and levels Alexander's disembodied voice asked me what I was doing, then after I set the weights I got the flash that suggested I'd completed a puzzle. I expected that organic residue to start covering everything but that didn't happen, not sure if it's supposed to or not?

Anyway. I appear to have completed the control room but nothing's changed out in the main room, the water level hasn't budged.. what do I do now?

[Frontcannon]

There are two levers near the door to the machine room which you can use to lower the bridges now.

I didn't see them the first time either.

[Evolution13]

Thanks!