I made mine out of CPVC. PVC is spec'ed according to the inside diameter of the pipe. Thus, a 3/4" PVC pipe wont fit into a 3/4" hose.
CPVC is measured according to it's outside diameter and a 3/4" CPVC pipe fits nicely into the end of a 3/4" hose, which is what I did.
I made mine the entire length of the tank with the holes angled upward. The water then circulates along the top, hits the front, goes down the front, back along the bottom, and then up along the back.
I also only glued the joints that hang outside the tank. This allows me to partially disassemble it for cleaning, and since the spray bars arent glued, they can be rotated and pointed in any direction you want.