diff --git a/OpenEphys.Onix/OpenEphys.Onix/ContextTask.cs b/OpenEphys.Onix/OpenEphys.Onix/ContextTask.cs
index 9e02bbb1..275dc944 100644
--- a/OpenEphys.Onix/OpenEphys.Onix/ContextTask.cs
+++ b/OpenEphys.Onix/OpenEphys.Onix/ContextTask.cs
@@ -145,7 +145,7 @@ void ConfigureResources(StackDisposable disposable, Func<ContextTask, IDisposabl
             }
         }
 
-        internal void Start()
+        internal void Start(int blockReadSize, int blockWriteSize)
         {
             lock (regLock)
             {
@@ -153,6 +153,8 @@ internal void Start()
 
                 // NB: Configure context before starting acquisition
                 ContextConfiguration = ConfigureContext();
+                ctx.BlockReadSize = blockReadSize;
+                ctx.BlockWriteSize = blockWriteSize;
 
                 // NB: Stuff related to sync mode is 100% ONIX, not ONI, so long term another place
                 // to do this separation might be needed
@@ -289,10 +291,6 @@ public int BlockReadSize
             {
                 return ctx.BlockReadSize;
             }
-            set
-            {
-                ctx.BlockReadSize = value;
-            }
         }
 
         public int BlockWriteSize
@@ -301,10 +299,6 @@ public int BlockWriteSize
             {
                 return ctx.BlockWriteSize;
             }
-            set
-            {
-                ctx.BlockWriteSize = value;
-            }
         }
 
         public PassthroughState HubState
diff --git a/OpenEphys.Onix/OpenEphys.Onix/StartAcquisition.cs b/OpenEphys.Onix/OpenEphys.Onix/StartAcquisition.cs
index 99c9dddb..e2a4468e 100644
--- a/OpenEphys.Onix/OpenEphys.Onix/StartAcquisition.cs
+++ b/OpenEphys.Onix/OpenEphys.Onix/StartAcquisition.cs
@@ -21,9 +21,7 @@ public class StartAcquisition : Combinator<ContextTask, oni.Frame>
                     var disposable = context.FrameReceived.SubscribeSafe(observer);
                     try
                     {
-                        context.BlockReadSize = ReadSize;
-                        context.BlockWriteSize = WriteSize;
-                        context.Start();
+                        context.Start(ReadSize, WriteSize);
                     }
                     catch
                     {