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Our entire hydronic system (GB142, indirect DHW tank, pex, rads, etc.) was installed about seven years ago. At that time the Buderus manual stipulated that no water treatment should be used. Since then, Buderus has issued a technical service bulletin mandating the use of one of four specific inhibitors. Each inhibitor manufacturer sells a cleaner that can be used as directed and then flushed prior to adding inhibitor. Assuming I should begin with a cleaning, I first did a practice run by flushing the entire system. Monitoring the drained water using a clear vinyl hose, I was impressed with the clean appearance of the water. Could a chemical cleaner be overkill? I'm tempted to skip cleaning and simply add sufficient inhibitor to establish a correct PH. I'd appreciate your advice. Fred