diff --git a/mlair/plotting/data_insight_plotting.py b/mlair/plotting/data_insight_plotting.py
index 45f5d3d6a451200d35c8f9085b31d3c394ae62b1..cc8ba279d556726ef82ac13e0287077215d6b4d6 100644
--- a/mlair/plotting/data_insight_plotting.py
+++ b/mlair/plotting/data_insight_plotting.py
@@ -803,13 +803,15 @@ class PlotPeriodogram(AbstractPlotClass):  # pragma: no cover
         plot_path = os.path.join(os.path.abspath(self.plot_folder), plot_name)
         logging.info(f"... plotting {plot_name}")
         pdf_pages = matplotlib.backends.backend_pdf.PdfPages(plot_path)
-        colors = ["blue", "red", "green", "orange", "purple", "black", "grey"]
+        colors = ["grey", "blue", "red", "green", "orange", "purple", "black"]
         label_names = ["orig"] + label_names
         max_iter = len(self.plot_data)
         var_keys = self.plot_data[0].keys()
         for var in var_keys:
             fig, ax = plt.subplots()
             for i in reversed(range(max_iter)):
+                if label_names[i] == "unfiltered":
+                    continue  # do not include the filter 'unfiltered' because this is equal to the 'orig' data
                 plot_data = self.plot_data[i]
                 c = colors[i]
                 ma = pd.DataFrame(np.vstack(plot_data[var]).T).rolling(5, center=True, axis=0)