This winter ive beeen using soft silicone tubing 4/6mm in green from my local koi centre its 35 quid for 100m roll but its worth it, I must say its the nutz , so far only winter testing not sure on its summer use yet, but looking good better than the black 4/6mm version I used beffore, it dont stiffen up like other stuff so much more manageable, its been matched too 6mm microbore hose reel with 1.5mm jets for interest.