River manifold turned on its head... really...

[Hokum]

Does anyone know if powerheads work ok upside down? As my tank is already all setup and this is going to be effectively a bolted on setup i'm thinking of running the tubes under the lip at the top of my tank (a clearseal 36x12x15) rather than under the gravel.

Has anyone else tried this?

[hx]

Powerheads work upside down.
Getting air out of the pipes is the hard part, especially if the pipes are above waterline. If you manage that, then there is no problem.

[Diana]

I would glue the pipes in a set up like this. (I do not glue them when they run under the gravel.)
So... measure very carefully as you are setting it up.