diff --git a/app/controllers/ingredients_controller.rb b/app/controllers/ingredients_controller.rb
index f9293b0..69340c0 100644
--- a/app/controllers/ingredients_controller.rb
+++ b/app/controllers/ingredients_controller.rb
@@ -69,7 +69,7 @@ class IngredientsController < BodyTrackingPluginController
   end
 
   def filter
-    session[:i_filters] = params[:filters]
+    session[:i_filters] = params.permit(:name, :visibility, formula: [:code, :zero_nil])
     prepare_items
     render :index
   end
@@ -178,7 +178,7 @@ class IngredientsController < BodyTrackingPluginController
   private
 
   def init_session_filters
-    session[:i_filters] ||= {}
+    session[:i_filters] ||= {formula: {}}
   end
 
   def ingredient_params
diff --git a/app/controllers/measurements_controller.rb b/app/controllers/measurements_controller.rb
index c8056a9..7562357 100644
--- a/app/controllers/measurements_controller.rb
+++ b/app/controllers/measurements_controller.rb
@@ -69,8 +69,7 @@ class MeasurementsController < BodyTrackingPluginController
   end
 
   def filter
-    session[:m_filters][:name] = params[:filters][:name]
-    session[:m_filters][:formula] = params[:filters][:formula]
+    session[:m_filters] = params.permit(:name, formula: [:code, :zero_nil])
     readouts_view? ? prepare_readouts : prepare_measurements
     render :index
   end
diff --git a/app/views/ingredients/_filters.html.erb b/app/views/ingredients/_filters.html.erb
index 7f7be6a..a92637e 100644
--- a/app/views/ingredients/_filters.html.erb
+++ b/app/views/ingredients/_filters.html.erb
@@ -9,20 +9,16 @@
     <table class="filter">
       <tr>
         <td>
-          <%= text_field_tag 'filters[name]', session[:i_filters][:name], placeholder: 'name',
-            onblur: '$("#filters-form").submit(); return false;' %>
+          <%= text_field_tag 'name', session[:i_filters][:name], placeholder: 'name' %>
         </td>
         <td>
-          <%= select_tag 'filters[visibility]',
-            visibility_options(session[:i_filters][:visibility]),
-            prompt: t('.visibility_prompt'),
-            onchange: '$("#filters-form").submit();' %>
+          <%= select_tag 'visibility', visibility_options(session[:i_filters][:visibility]),
+            prompt: t('.visibility_prompt'), onchange: '$("#filters-form").submit();' %>
         </td>
         <td style="width:100%;">
-          <%= text_field_tag 'filters[formula]', session[:i_filters][:formula],
+          <%= text_field_tag 'formula[code]', session[:i_filters][:formula][:code],
             placeholder: 'conditional expression including nutrients', size: 40,
-            style: 'box-sizing:border-box; width:100%;',
-            onblur: '$("#filters-form").submit(); return false;' %>
+            style: 'box-sizing:border-box; width:100%;' %>
         </td>
         <td>
           <%= link_to l(:button_apply), '#', class: "icon icon-checked",
@@ -34,7 +30,20 @@
                       $("#filters-form").submit(); return false;' %>
         </td>
       </tr>
+      <tr>
+        <td></td>
+        <td></td>
+        <td style="padding-top:4px;">
+          <%= label_tag do %>
+            <%= check_box_tag 'formula[zero_nil]', session[:i_filters][:formula][:zero_nil] %>
+            <%= t 'quantities.form.zero_nil' %>
+          <% end %>
+        </td>
+        <td></td>
+        <td></td>
+      </tr>
     </table>
+    <%= submit_tag '', style: 'display:none;' %>
     <% end %>
   </div>
 </fieldset>
diff --git a/app/views/ingredients/_nutrients.html.erb b/app/views/ingredients/_nutrients.html.erb
index a3f3582..befb575 100644
--- a/app/views/ingredients/_nutrients.html.erb
+++ b/app/views/ingredients/_nutrients.html.erb
@@ -4,7 +4,7 @@
 <% if @ingredients.any? %>
   <%= render partial: 'ingredients/options' %>
 
-  <%= error_messages_for *@quantities.map { |q| q.formula } %>
+  <%= error_messages_for @formula_q.formula, *@quantities.map { |q| q.formula } %>
 
   <table class="nutrients list odd-even">
     <thead>
diff --git a/app/views/measurements/_filters.html.erb b/app/views/measurements/_filters.html.erb
index c33edc5..cbbe94a 100644
--- a/app/views/measurements/_filters.html.erb
+++ b/app/views/measurements/_filters.html.erb
@@ -9,14 +9,12 @@
     <table class="filter">
       <tr>
         <td>
-          <%= text_field_tag 'filters[name]', session[:m_filters][:name], placeholder: 'name',
-            onblur: '$("#filters-form").submit(); return false;' %>
+          <%= text_field_tag 'name', session[:m_filters][:name], placeholder: 'name' %>
         </td>
         <td style="width:100%;">
-          <%= text_field_tag 'filters[formula][code]', session[:m_filters][:formula][:code],
+          <%= text_field_tag 'formula[code]', session[:m_filters][:formula][:code],
             placeholder: 'conditional expression including readouts', size: 40,
-            style: 'box-sizing:border-box; width:100%;',
-            onblur: '$("#filters-form").submit(); return false;' %>
+            style: 'box-sizing:border-box; width:100%;' %>
         </td>
         <td>
           <%= link_to l(:button_apply), '#', class: "icon icon-checked",
@@ -32,8 +30,7 @@
         <td></td>
         <td style="padding-top:4px;">
           <%= label_tag do %>
-            <%= check_box_tag 'filters[formula][zero_nil]',
-              session[:m_filters][:formula][:zero_nil] %>
+            <%= check_box_tag 'formula[zero_nil]', session[:m_filters][:formula][:zero_nil] %>
             <%= t 'quantities.form.zero_nil' %>
           <% end %>
         </td>
@@ -41,6 +38,7 @@
         <td></td>
       </tr>
     </table>
+    <%= submit_tag '', style: 'display:none;' %>
     <% end %>
   </div>
 </fieldset>
diff --git a/lib/body_tracking/items_with_quantities.rb b/lib/body_tracking/items_with_quantities.rb
index c948047..36c17af 100644
--- a/lib/body_tracking/items_with_quantities.rb
+++ b/lib/body_tracking/items_with_quantities.rb
@@ -23,8 +23,8 @@ module BodyTracking
       project = proxy_association.owner
       domain = QUANTITY_DOMAINS[proxy_association.klass]
       formula_q = if filters[:formula].present?
-                    project.quantities.new(name: '__internal_q',
-                                           formula: filters[:formula],
+                    project.quantities.new(name: 'Filter formula',
+                                           formula_attributes: filters[:formula],
                                            domain: domain)
                   end
       apply_formula = formula_q.present? && formula_q.valid?
@@ -89,7 +89,7 @@ module BodyTracking
           begin
             calculated = q.formula.calculate(inputs.to_h)
           rescue Exception => e
-            output_ids.each { |oid| subitems[q.name][oid] = BigDecimal::NAN }
+            output_ids.each { |oid| subitems[q.name][oid] = [BigDecimal::NAN, nil] }
             q.formula.errors.add(:code, :computation_failed,
               {quantity: q.name, description: e.message, count: output_ids.size})
           else