Processing methods and apparatus for depositing a protective layer on internal surfaces of a reaction chamber are provided. One method may include depositing, while no wafers are present in the reaction chamber having interior surfaces, a first layer of protective material onto the interior surfaces, the interior surfaces comprising a first material, processing, after the depositing the first layer, a portion of a batch of wafers within a reaction chamber, measuring an amount of the first material in the reaction chamber during processing the portion of the batch of wafers, or on one of the wafers in the portion of the batch of wafers, determining that the first amount exceeds a threshold, and depositing, in response to determining that the first amount exceeds the threshold and while no wafers are present in the reaction chamber, a second layer of protective material onto the interior surfaces of the reaction chamber.