Started with low lift pump pressure.I have emptied and dropped tank and am replacing hoses. Have been provided with a hard, relatively inflexible nylon hose for return system. It has a snap on setting and I am supposed to be able to heat it in hot water to expand it enough to fit on the steel tube. It is not expanding enough to work. Question is: Do I need this substantial of a high pressure tube for this return line? Very frustrated. HEEELP!