I personally don't let soap anywhere near my fish stuff. It's nearly impossible to get all soap residue off of anything. Soap is NOT good for your fish. I simply use hot water. Fill up the sink...then fill up the hose...leave it soaking in the hot water for a while. After soaking, do your best to send some higher pressure water through the hose.
If you're having hard water deposits, add some vinegar to the water you're soaking in.
If the host is really bad...just buy new hose, even if you have a 100' python, new hose is only a few bucks.