diff --git a/Code/Mantid/instrument/ARCS_Parameters.xml b/Code/Mantid/instrument/ARCS_Parameters.xml
index 2808f21f930b447aff3b01d88465d101925283b8..74a18da8c8dbdd6fabc897bb2e8ddd80cbe8c079 100644
--- a/Code/Mantid/instrument/ARCS_Parameters.xml
+++ b/Code/Mantid/instrument/ARCS_Parameters.xml
@@ -62,7 +62,7 @@
 
 		<!-- Remove zeroes in background (s_zero)-->
 		<parameter name="diag_samp_zero">
-		  <value val="1.0"/>
+		  <value val="0.0"/>
 		</parameter>
 
 		<!-- Fraction of median to consider counting low for the white beam diag (sv_lo)-->
diff --git a/Code/Mantid/instrument/CNCS_Parameters.xml b/Code/Mantid/instrument/CNCS_Parameters.xml
index 7b76b3d20ceb8ae7e1de60d392bc641c716b3ceb..6b5766063d7c5ae9b09d8dccc3d63e576fd9fa40 100644
--- a/Code/Mantid/instrument/CNCS_Parameters.xml
+++ b/Code/Mantid/instrument/CNCS_Parameters.xml
@@ -62,7 +62,7 @@
 
 		<!-- Remove zeroes in background (s_zero)-->
 		<parameter name="diag_samp_zero">
-		  <value val="1.0"/>
+		  <value val="0.0"/>
 		</parameter>
 
 		<!-- Fraction of median to consider counting low for the white beam diag (sv_lo)-->
diff --git a/Code/Mantid/instrument/HYSPECA_Parameters.xml b/Code/Mantid/instrument/HYSPECA_Parameters.xml
index b370df4b9daba7dbb7d8f46f19e529213ff5d3d1..bfe1144d99003c70a1e718adf37028e2ec254d12 100644
--- a/Code/Mantid/instrument/HYSPECA_Parameters.xml
+++ b/Code/Mantid/instrument/HYSPECA_Parameters.xml
@@ -62,7 +62,7 @@
 
 		<!-- Remove zeroes in background (s_zero)-->
 		<parameter name="diag_samp_zero">
-		  <value val="1.0"/>
+		  <value val="0.0"/>
 		</parameter>
 
 		<!-- Fraction of median to consider counting low for the white beam diag (sv_lo)-->
diff --git a/Code/Mantid/instrument/HYSPEC_Parameters.xml b/Code/Mantid/instrument/HYSPEC_Parameters.xml
index 2632a7e47f5f1c37e2892a982245783bb42e19a3..6d67410f585c696d4f52d85fe9d93f78a677c641 100644
--- a/Code/Mantid/instrument/HYSPEC_Parameters.xml
+++ b/Code/Mantid/instrument/HYSPEC_Parameters.xml
@@ -62,7 +62,7 @@
 
 		<!-- Remove zeroes in background (s_zero)-->
 		<parameter name="diag_samp_zero">
-		  <value val="1.0"/>
+		  <value val="0.0"/>
 		</parameter>
 
 		<!-- Fraction of median to consider counting low for the white beam diag (sv_lo)-->
diff --git a/Code/Mantid/instrument/SEQUOIA_Parameters.xml b/Code/Mantid/instrument/SEQUOIA_Parameters.xml
index 45f188458a3618e8bee12603330018a28d7d13e3..ed3d73a2754b4ff4048943d346bbea4877e414fc 100644
--- a/Code/Mantid/instrument/SEQUOIA_Parameters.xml
+++ b/Code/Mantid/instrument/SEQUOIA_Parameters.xml
@@ -51,7 +51,7 @@
 
 		<!-- Remove zeroes in background (s_zero)-->
 		<parameter name="diag_samp_zero">
-		  <value val="1.0"/>
+		  <value val="0.0"/>
 		</parameter>
 
 		<!-- Fraction of median to consider counting low for the white beam diag (sv_lo)-->