Converting IC to counterflow: how to clean inside of copper tube

So I'm going to make a counterflow chiller with the copper from my IC. Because I never thought I would be pumping beer through my IC I never gave it good care to make sure no water was left inside when not in use.

So I begin disassembling my IC and notice there is a lot of blue corrosion inside the tube which is expected. I figured a good soak in some vinegar would do the trick. So I hooked up my carboy/keg cleaner to my IC and recirculated vinegar/water through the pipe. I let if soak for several days while periodically turning on the pump.

The end result was blue vinegar water (dissolved copper) and a much cleaner looking inside. But I did notice a kind of red tint inside the tube (for the very small portion I could see) that made me wonder how clean it actually was. So I inserted my line cleaner brush just to see if it would come off. And it does, it made the brush turn brown/red kind of rust looking.

So my qqiestion is, what do I do now? How is the best way to clean this or should I just buy new 3/8" tubing for this? Maybe circulate some pbw and another vinegar round through the tubing?

Trys some diluted StarSan on it.
Yet another acid, phosphoric vs. the acetic you already used.
Do the soak and circulate thing, and see if it removes said redness.

I would be interested to know your results, and hopefully someone will chime in, lest I be leadin' you astray, but I think you are O K with the StarSan traetment, and I don't think it will take as long to see your results, say , 24 hrs. or less.

I would also think that filling the chiller with water then immersing it in a boil for 15 minutes would be a good rinse.

How's your ground water temperature in summer? It might be easier to use your IC in an ice bucket as a water prechiller if you need one and build a CFC from scratch.

Plus you can brew again using the IC before you finish debugging the CFC.