Sorry to highjack the thread, but it does apply in that a solid cleaning regimine is part of any counterflow chiller setup.
I'm just always amazed at how lax people get about cleaning counterflow type chiller just because they can't see it.
Any flow inside a counterflow/plate chiller is a steady even flow. For comparison, try cleaning your boil kettle by dribbling water out of a pitcher. If you can't touch it, you have to use a chemical cleaner. Simply rinsing it ESPECIALLY on the cold side will ONLY lead to problems. I assure you, you wouldn't want to drink a commercial brewery that treats their equipemnt like that and I sure wouldn't want to drink homebrew like that either.