I would just use an RV water hose (for drinking water). That should be stiff enough. <There are also extra stiff double thick vinyl hoses at my local HD if you want to check that.> I got a 25' one at Walmart for $6 or so. There are longer ones as well, but since these have standard couplings at each end, you can join as many as needed to make any length you want.
My filler is a DIY version so I don't have a python to check, but I remember peole saying that this will fit the "real" python. <The RV hoses are usu 5/8" ID, although you can get 3/4"ID; but you should be able to connect the python using the standard garden hose couplings?>
80 gal FW with 30 gal DIY wet/dry/sump.
9 fancy golds, 1 hillstream loaches, 1 rubber-lip pleco (C. thomasi), 3 SAEs, small school of white cloud minnows, planted.