diff --git a/addons/f2_control/f2_control/controller.py b/addons/f2_control/f2_control/controller.py
index 02d18e4..decc298 100644
--- a/addons/f2_control/f2_control/controller.py
+++ b/addons/f2_control/f2_control/controller.py
@@ -651,7 +651,12 @@ def _params(self, room, zone):
             ec_target_p2=self._zone_num(room, zone, f"ec_target_{sfx}_p2", 6),
             p3_emergency_floor=efloor,
             p3_emergency_shot=self._zone_num(room, zone, "p3_emergency_shot_size", 2),
-            max_daily_volume=self._zone_num(room, zone, "max_daily_volume", 300),
+            # Fallback used ONLY when a zone has no readable max_daily_volume entity — e.g. a zone the
+            # engine detected from its VWC sensor but the integration never built a cap entity for
+            # (num_zones < detected zones). Must fail LOW: the integration's own entity maxes at 200 L,
+            # so the engine can never grant more daily water than the UI can express. Was 300 (above the
+            # UI max) which let orphaned zones free-run to 300 L/day while wired zones honoured their cap.
+            max_daily_volume=self._zone_num(room, zone, "max_daily_volume", 150),
             field_capacity=fc,
             max_ec=self._zone_num(room, zone, "maximum_ec", 9),
             stacking_on=self._on(