It is best to use car heater hose (NAPA etc) for inside the pump shelter and to get out of the shelter to the ground connection for black poly underground line. Rubber heater bends around tight curves easily, withstands the heat and resists kinking. The problem that I have with the black poly in the shelter is after time you can't get the black poly off the fittings. You almost have to cut them off when you have to do any maintenance on the compressor . With the heater hose it always easily pulls off all connections.
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