diff --git a/app.py b/app.py
index b17dc55..7b55582 100644
--- a/app.py
+++ b/app.py
@@ -170,7 +170,7 @@ class renderedImageZoom:
         p_frame = tkinter.Frame(self.aerosol_window)
         text_p = tkinter.Text(p_frame,height=1,width=10)
         submit_p_button = tkinter.Button(p_frame,text="set pressure",command=lambda: [self.set_press(text_p.get("1.0","end-1c")),
-                                                                                      p_label.config(text=str(sorted([400,int(text_p.get("1.0","end-1c")),900])[1]) +" mmHg")])
+                                                                                      p_label.config(text=str(sorted([0,int(text_p.get("1.0","end-1c")),900])[1]) +" mmHg")])
         p_label = tkinter.Label(p_frame,text="720 mmHg")
         text_p.pack(side=tkinter.LEFT)
         p_label.pack(side=tkinter.RIGHT)
@@ -287,8 +287,8 @@ class renderedImageZoom:
     def set_press(self,press):
         if press is None:
             self.pressure = 720
-        elif int(press) < 400 or int(press) > 900:
-            pressure = sorted([400,int(press),900])[1]
+        elif int(press) < 0 or int(press) > 900:
+            pressure = sorted([0,int(press),900])[1]
             print("pressure unrealistic, resetting to clamped value {}".format(pressure))
             self.pressure = pressure
         else: