Just take this as another data point. I don't use any cleaners at all on my copper tube-garden hose chiller. I think the biggest contributor to "funk" in the chiller occurs between uses. The copper tube can never completely dry out, therefore there is moisture + air + time = mold.
In my case, I just flush it really good with high velocity water from the hose right after use, then fill it with Iodophor and cap the ends. It is now 100% full of sanitizer, so nothing grows. Even if the sanitizer breaks down, there is no air to contribute to "funk" growth. When I go to use it again, I flush it out with water again, refill with fresh Iodophor, let it sit for 5 or 10 minutes, drain out the Iodophor and use it.
If it never dries out, no real crud can collect, therefore rinsing is very effective at getting "stuff" out as long as you do it right after you use it. About once a year (about 100 gallons of beer later), I'll flush it with PBW, but I've gone as long as 2 years without doing that and there are no ill effects. This has been my practice for the last 5 years.
Like I said, just another data point. I would never say cleaning it every time is a wasted effort.
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