Some small basic points may help. One is that the black stuff is often ABS, rather than PVC which may ease the finding it in stores or online. Also keep in mind that painting PVC, which is easier to find, also works well.
I've thought about that, but just assumed painted PVC in the tank water would cause contaminant issues. Is this not really a concern?
My 2 cents concerning your plan: I doubt you will achieve a circular flow over 96" (48"L× 2) with just one outlet pointed across the tank; current likely wont flow around and back to your filter intake. Also, a spray bar or outlet on a front corner just adds clutter to your tank. I would recommend junking the top too, it serves no purpose except reducing evaporation, which isn't important either.
What I did on my 42"L tank is is mount the filter input and output in the same back corner. The output is pointed diagonally toward about center of the front panel, or less. To keep the circular flow going across the back I mounted an Eheim surface skimmer in the opposite back corner. This set up works great and gives you surface skimming, which I think is important.
I figured the suction of the pump would be enough flow to circulate it back across the tank. The filter is rated for 400GPH, so there's plenty of juice there, even with filter media in place. I do have an Eheim skimmer, may end up using it after all. Regarding clutter, I have a framed tank, I think I'll be able to hid most of it behind the frame.
Interesting design. Consider running the top pipe running the width of the tank as a spray bar with the outlets pointed about a third downward. I was thinking of doing something similar with my 40B when I finally set it up. I may make my own spray bar from 1/2" CPVC pipe and I might run it from the back using a couple of heater clamps to secure it to the plastic strip at the back of my glass hood. In keeping with the no pipe look, have you considered an in-line heater like the Hydor? Also, an inexpensive UV filter plumbed in-line might be a good idea. I have one on all of my tanks except the 10g.
Thanks, I'm actually curious to see how it will work out. As far as I can tell, it should be no different than running a discharge line up the side of the tank. I've found a spray bar back to front was inadequate. Maybe I just needed larger holes. Doing it this way I get the full discharge force of the filter across the length of the tank, instead of bouncing it off the glass at varying angles.
All the inline stuff is on my wish list. Eventually I'll get to implement it into my system.