What kind of tubing to use for immersion chiller?

I am using this immersion chiller and I bought some PET tubing, I did a test run by placing it and the tubing into boiling water and the PET softened and I had cooling water flowing into my brew pot (only water was in the brew pot since it was a test so no big deal). I need to replace the tubing.

What kind of tubing should I buy? I need something that will not give a funny taste (or worse) to my wort, and something that can withstand high temperatures and not soften and flood my wort and ruin my brewing run.

oh, and fyi, its actually a kind of radiator (see my "what did I just buy" thread in equipment). I fitted it with brass fittings to squeeze onto 3/8" tubing and I've got one side hooked to the garden hose... so the tubing needs to be immersed in boiling wort with the "chiller"... aside from the leakage it works amazingly well

3/8 inch copper pipe. copper is ideal as it has a low heat capacity and it acts as a heat exchanger. I would not recommend using plastic.

You mean rigging up pipes to stick up out of it out of boiling liquid, and hooking the tubing up to that... at some point its going to need tubing.

Why don't you pump the wort through the plate chiller while it's immersed in an ice bath? Seems like an better application for that style of plate chiller?

and silicone tubing would be a nice choice for the tubing for both applications.

I'm just not sure how clean the inside is, but I did think about that. Anyway thanks for the suggestions.