diff --git a/app/assets/javascripts/editor.js b/app/assets/javascripts/editor.js
index cf57c08f..f67d1fb5 100644
--- a/app/assets/javascripts/editor.js
+++ b/app/assets/javascripts/editor.js
@@ -1127,6 +1127,10 @@ $(function() {
 
   var initTurtle = function() {
       // todo guard clause if turtle is not required for the current exercise
+
+      // clear canvas
+      // turtlecanvas.getContext("2d").clearRect(0, 0, turtlecanvas.width, turtlecanvas.height);
+
       turtlescreen = new Turtle(websocket, turtlecanvas);
       if ($('#run').isPresent()) {
         $('#run').bind('click', hideCanvas);
diff --git a/app/controllers/submissions_controller.rb b/app/controllers/submissions_controller.rb
index 13435a46..62301102 100644
--- a/app/controllers/submissions_controller.rb
+++ b/app/controllers/submissions_controller.rb
@@ -112,13 +112,13 @@ class SubmissionsController < ApplicationController
         end
 
         tubesock.onmessage do |data|
-          Rails.logger.info("Client sending: " + data)
+          Rails.logger.debug("Client sending: " + data)
           # Check wether the client send a JSON command and kill container
           # if the command is 'exit', send it to docker otherwise.
           begin
             parsed = JSON.parse(data)
             if parsed['cmd'] == 'exit'
-              Rails.logger.info("Client exited container.")
+              Rails.logger.debug("Client exited container.")
               @docker_client.exit_container(result[:container])
             else
               socket.send data
@@ -209,6 +209,7 @@ class SubmissionsController < ApplicationController
   end
 
   def stop
+    Rails.logger.debug('stopping submission ' + @submission)
     container = Docker::Container.get(params[:container_id])
     DockerClient.destroy_container(container)
   rescue Docker::Error::NotFoundError
diff --git a/config/environments/development.rb b/config/environments/development.rb
index 9ceddb73..a91cebc2 100644
--- a/config/environments/development.rb
+++ b/config/environments/development.rb
@@ -1,6 +1,7 @@
 Rails.application.configure do
   # Settings specified here will take precedence over those in config/application.rb.
 
+  config.web_console.whitelisted_ips = '192.168.0.0/16'
   # In the development environment your application's code is reloaded on
   # every request. This slows down response time but is perfect for development
   # since you don't have to restart the web server when you make code changes.
diff --git a/lib/docker_client.rb b/lib/docker_client.rb
index a2792498..4a353394 100644
--- a/lib/docker_client.rb
+++ b/lib/docker_client.rb
@@ -97,6 +97,7 @@ class DockerClient
     container.status = :created
     container
   rescue Docker::Error::NotFoundError => error
+    Rails.logger.info('create_container: Got Docker::Error::NotFoundError: ' + error)
     destroy_container(container)
     #(tries += 1) <= RETRY_COUNT ? retry : raise(error)
   end
@@ -176,7 +177,7 @@ class DockerClient
       timeout = @execution_environment.permitted_execution_time.to_i # seconds
       sleep(timeout)
       if container.status != :returned
-        Rails.logger.info("Killing container after timeout of " + timeout.to_s + " seconds.")
+        Rails.logger.info('Killing container after timeout of ' + timeout.to_s + ' seconds.')
         # send timeout to the tubesock socket
         if(@tubesock)
           @tubesock.send_data JSON.dump({'cmd' => 'timeout'})
@@ -187,6 +188,7 @@ class DockerClient
   end
 
   def exit_container(container)
+    Rails.logger.debug('exiting container ' + container.to_s)
     # exit the timeout thread if it is still alive
     if(@thread && @thread.alive?)
       @thread.exit
@@ -196,6 +198,7 @@ class DockerClient
   end
 
   def kill_container(container)
+    Rails.logger.info('killing container ' + container.to_s)
     # remove container from pool, then destroy it
     if (DockerContainerPool.config[:active])
       DockerContainerPool.remove_from_all_containers(container, @execution_environment)
@@ -215,7 +218,7 @@ class DockerClient
     """
     Run commands by attaching a websocket to Docker.
     """
-    command = submission.execution_environment.send(:"run_command") % command_substitutions(filename)
+    command = submission.execution_environment.run_command % command_substitutions(filename)
     create_workspace_files = proc { create_workspace_files(container, submission) }
     execute_websocket_command(command, create_workspace_files, block)
   end
@@ -224,7 +227,7 @@ class DockerClient
     """
     Stick to existing Docker API with exec command.
     """
-    command = submission.execution_environment.send(:"test_command") % command_substitutions(filename)
+    command = submission.execution_environment.test_command % command_substitutions(filename)
     create_workspace_files = proc { create_workspace_files(container, submission) }
     execute_command(command, create_workspace_files, block)
   end
@@ -282,6 +285,7 @@ class DockerClient
   end
 
   def self.return_container(container, execution_environment)
+    Rails.logger.debug('returning container ' + container.to_s)
     clean_container_workspace(container)
     DockerContainerPool.return_container(container, execution_environment)
     container.status = :returned
diff --git a/lib/docker_container_pool.rb b/lib/docker_container_pool.rb
index daa75242..d027076b 100644
--- a/lib/docker_container_pool.rb
+++ b/lib/docker_container_pool.rb
@@ -30,14 +30,15 @@ class DockerContainerPool
     if(!@containers[execution_environment.id].include?(container))
       @containers[execution_environment.id]+=[container]
     else
-      Rails.logger.info('failed trying to add existing container ' + container.to_s)
+      Rails.logger.info('failed trying to add existing container ' + container.to_s + ' to execution_environment ' + execution_environment.to_s)
     end
   end
 
   def self.create_container(execution_environment)
-     container = DockerClient.create_container(execution_environment)
-     container.status = 'available'
-     container
+    container = DockerClient.create_container(execution_environment)
+    container.status = 'available'
+    Rails.logger.debug('created container ' + container.to_s + ' for execution environment ' + execution_environment.to_s)
+    container
   end
 
   def self.return_container(container, execution_environment)
@@ -45,7 +46,7 @@ class DockerContainerPool
     if(@containers[execution_environment.id] && !@containers[execution_environment.id].include?(container))
       @containers[execution_environment.id].push(container)
     else
-      Rails.logger.info('trying to return existing container ' + container.to_s)
+      Rails.logger.info('trying to return existing container ' + container.to_s + ' to execution_environment ' + execution_environment.to_s)
     end
   end
 
@@ -53,11 +54,11 @@ class DockerContainerPool
     # if pooling is active, do pooling, otherwise just create an container and return it
     if config[:active]
       container = @containers[execution_environment.id].try(:shift) || nil
-      Rails.logger.info('get_container fetched container  ' + container.to_s)
+      Rails.logger.debug('get_container fetched container  ' + container.to_s + ' for execution environment ' + execution_environment.to_s)
       # just access and the following if we got a container. Otherwise, the execution_environment might be just created and not fully exist yet.
       if(container)
-        Rails.logger.info('get_container remaining avail. containers:  ' + @containers[execution_environment.id].size.to_s)
-        Rails.logger.info('get_container all container count: ' + @all_containers[execution_environment.id].size.to_s)
+        Rails.logger.debug('get_container remaining avail. containers:  ' + @containers[execution_environment.id].size.to_s)
+        Rails.logger.debug('get_container all container count: ' + @all_containers[execution_environment.id].size.to_s)
       end
       container
     else
@@ -82,10 +83,13 @@ class DockerContainerPool
   def self.refill_for_execution_environment(execution_environment)
     refill_count = [execution_environment.pool_size - @all_containers[execution_environment.id].length, config[:refill][:batch_size]].min
     if refill_count > 0
-      Rails.logger.info('adding ' + refill_count.to_s + ' containers for  ' +  execution_environment.name )
+      Rails.logger.info('Adding ' + refill_count.to_s + ' containers for execution_environment ' +  execution_environment.name )
       c = refill_count.times.map { create_container(execution_environment) }
+      Rails.logger.debug('Created containers: ' + c.to_s )
       @containers[execution_environment.id] += c
       @all_containers[execution_environment.id] += c
+      Rails.logger.debug('@containers ' + @containers.object_id.to_s + ' has:'+ @containers[execution_environment.id].to_s)
+      Rails.logger.debug('@all_containers '  + @containers.object_id.to_s + ' has:'+ @all_containers[execution_environment.id].to_s)
       #refill_count.times.map { create_container(execution_environment) }
     end