in addition to that question, let me go further....
I am in the process of doing the plumbing for my tank and in need off some king of flexible hose for the pressure lines from my pumps back the the tank....
I attempted to do hard lines (PVC pipe) but just do not have enough room for all the 45degree bends that would be required to not kill flow.....
Always use flex pvc when pluming a return. there are two reasons, 1 the pumpp will run quieter, 2 less back pressure. Each 45 you use adds 3/4' of head on your pump. I hard pumbed my first tank man was that thing loud. If you want that drain hose pm me I have a 3' piece new and I can get you longer pieces if you want them.