Interesting... not to dismiss Lee's original point, I know some reefers deliberately don't dip chaeto because it contains a lot of pods and other good stuff.
I've had red flatworms too. I got excited, and dipped a lot of the corals I found them on. Killed a couple of corals that way... The flatworms got siphoned out with water changes, and they just disappeared later. Here's a nice article from the excellent
Melev's Reef site.
AFAIK, they don't eat corals, but they can "smother" them when they get to plague proportions. When they die off, they release a toxin which can be harmful if it is too concentrated (too many at once).
Anyway, like so many other reef pests, they seem to come and go peacefully most of the time for most folks. When they do find the right balance for population explosion, they can apparently become quite a problem. I'd safe the "exit" products for those times.
BTW, the white ones aren't considered a problem, most of the time.
Back to the OP's point. Dipping / QT: good.
