i just use normal gardiner yellow reel hose with no issues but the all season pole hose turns to silly string so i bought some of the gardiner red thermobore pole hose which softens just right when warm but a dam pain when cold.
the biggest issue i had was the outlet side of the heater to the reel,being the hottest bit i swapped from normal garden hose to the clear reinforced stuff with double jubilee clips and its been spot on since.