Tygon if you really got cash onli go for it... its very expensive... coz its used for medical and laboratory use with very high quality standards. the R3603 formulation is resistant to alkaline's, acides and organic solvents and many other chemicals.
otherwise go for oil tubings will do... or gas tubings but gas tubings are a little stiffer.
Oil tubings are stiffer than tygons. tygons are soft and very flexible, but then again, you pay the premium price for it.
eheim tubings are also not bad, juz that i couldnt find the appropriate 1/2" ID 3/4" OD size. however, they have a strong green tint to it.

This post has been edited by MetalZone: Apr 22 2006, 03:34 AM

Here... for my budget kit.
http://forum.lowyat.net/index.php?showtopic=219878&st=320