diff --git a/app/controllers/comments_controller.rb b/app/controllers/comments_controller.rb
index 076b33fce..f07507600 100644
--- a/app/controllers/comments_controller.rb
+++ b/app/controllers/comments_controller.rb
@@ -1,15 +1,13 @@
 class CommentsController < ApplicationController
   before_action :authenticate_user!
+  before_action :load_commentable, only: :create
   before_action :build_comment, only: :create
-  before_action :parent, only: :create
 
   load_and_authorize_resource
   respond_to :html, :js
 
   def create
     if @comment.save
-      @comment.move_to_child_of(parent) if reply?
-
       Mailer.comment(@comment).deliver_now if email_on_debate_comment?
       Mailer.reply(@comment).deliver_now if email_on_comment_reply?
     else
@@ -37,11 +35,11 @@ class CommentsController < ApplicationController
   private
 
     def comment_params
-      params.require(:comment).permit(:commentable_type, :commentable_id, :body, :as_moderator, :as_administrator)
+      params.require(:comment).permit(:commentable_type, :commentable_id, :parent_id, :body, :as_moderator, :as_administrator)
     end
 
     def build_comment
-      @comment = Comment.build(debate, current_user, comment_params[:body])
+      @comment = Comment.build(@commentable, current_user, comment_params[:body], comment_params[:parent_id].presence)
       check_for_special_comments
     end
 
@@ -53,24 +51,16 @@ class CommentsController < ApplicationController
       end
     end
 
-    def debate
-      @debate ||= Debate.find(params[:debate_id])
-    end
-
-    def parent
-      @parent ||= Comment.find_parent(comment_params)
-    end
-
-    def reply?
-      parent.class == Comment
+    def load_commentable
+      @commentable = Comment.find_commentable(comment_params[:commentable_type], comment_params[:commentable_id])
     end
 
     def email_on_debate_comment?
-      @comment.debate.author.email_on_debate_comment?
+      @comment.commentable.author.email_on_debate_comment?
     end
 
     def email_on_comment_reply?
-      reply? && parent.author.email_on_comment_reply?
+      @comment.reply? && @comment.parent.author.email_on_comment_reply?
     end
 
     def administrator_comment?
diff --git a/app/controllers/debates_controller.rb b/app/controllers/debates_controller.rb
index 451d8e893..865eadced 100644
--- a/app/controllers/debates_controller.rb
+++ b/app/controllers/debates_controller.rb
@@ -14,9 +14,10 @@ class DebatesController < ApplicationController
 
   def show
     set_debate_votes(@debate)
-    @comments = @debate.root_comments.recent.page(params[:page]).for_render
+    @commentable = @debate
+    @comments = @debate.comments.roots.recent.page(params[:page]).for_render
     # TODO limit this list to the paginated root comment's children once we have ancestry
-    all_visible_comments = @debate.comment_threads
+    all_visible_comments = @debate.comments
     set_comment_flags(all_visible_comments)
   end
 
diff --git a/app/helpers/comments_helper.rb b/app/helpers/comments_helper.rb
index 14dabf49c..300a07921 100644
--- a/app/helpers/comments_helper.rb
+++ b/app/helpers/comments_helper.rb
@@ -8,4 +8,8 @@ module CommentsHelper
     parent_id.present?  ? t("comments_helper.reply_button") : t("comments_helper.comment_button")
   end
 
+  def parent_or_commentable_dom_id(parent_id, commentable)
+    parent_id.blank? ? dom_id(commentable) : "comment_#{parent_id}"
+  end
+
 end
\ No newline at end of file
diff --git a/app/models/comment.rb b/app/models/comment.rb
index 77cbd166e..fe57ee95f 100644
--- a/app/models/comment.rb
+++ b/app/models/comment.rb
@@ -1,13 +1,15 @@
 class Comment < ActiveRecord::Base
-  acts_as_nested_set scope: [:commentable_id, :commentable_type], counter_cache: :children_count
+  #acts_as_nested_set scope: [:commentable_id, :commentable_type], counter_cache: :children_count
   acts_as_paranoid column: :hidden_at
   include ActsAsParanoidAliases
   acts_as_votable
+  has_ancestry
 
   attr_accessor :as_moderator, :as_administrator
 
   validates :body, presence: true
   validates :user, presence: true
+  validates_inclusion_of :commentable_type, in: ["Debate"]
 
   belongs_to :commentable, -> { with_hidden }, polymorphic: true, counter_cache: true
   belongs_to :user, -> { with_hidden }
@@ -23,14 +25,15 @@ class Comment < ActiveRecord::Base
 
   scope :for_render, -> { with_hidden.includes(user: :organization) }
 
-  def self.build(commentable, user, body)
+  def self.build(commentable, user, body, p_id=nil)
     new commentable: commentable,
         user_id:     user.id,
-        body:        body
+        body:        body,
+        parent_id:   p_id
   end
 
-  def self.find_parent(params)
-    params[:commentable_type].constantize.find(params[:commentable_id])
+  def self.find_commentable(c_type, c_id)
+    c_type.constantize.find(c_id)
   end
 
   def debate
@@ -86,7 +89,11 @@ class Comment < ActiveRecord::Base
   end
 
   def after_hide
-    commentable_type.constantize.reset_counters(commentable_id, :comment_threads)
+    commentable_type.constantize.reset_counters(commentable_id, :comments)
+  end
+
+  def reply?
+    !root?
   end
 
 end
diff --git a/app/models/debate.rb b/app/models/debate.rb
index 9c96c812c..6f0543caf 100644
--- a/app/models/debate.rb
+++ b/app/models/debate.rb
@@ -6,13 +6,13 @@ class Debate < ActiveRecord::Base
   TITLE_LENGTH = Debate.columns.find { |c| c.name == 'title' }.limit
 
   acts_as_votable
-  acts_as_commentable
   acts_as_taggable
   acts_as_paranoid column: :hidden_at
   include ActsAsParanoidAliases
 
   belongs_to :author, -> { with_hidden }, class_name: 'User', foreign_key: 'author_id'
   has_many :flags, :as => :flaggable
+  has_many :comments, as: :commentable
 
   validates :title, presence: true
   validates :description, presence: true
diff --git a/app/views/comments/_comment.html.erb b/app/views/comments/_comment.html.erb
index e02cb4c48..ba9e99151 100644
--- a/app/views/comments/_comment.html.erb
+++ b/app/views/comments/_comment.html.erb
@@ -49,7 +49,7 @@
                 <%= t("shared.collective") %>
               </span>
             <% end %>
-            <% if comment.user_id == @debate.author_id %>
+            <% if comment.user_id == @commentable.author_id %>
               &nbsp;&bullet;&nbsp;
               <span class="label round is-author">
                 <%= t("debates.comment.author") %>
@@ -65,11 +65,11 @@
           <p class="comment-user is-admin"><%= comment.body %></p>
         <% elsif comment.as_moderator? %>
           <p class="comment-user is-moderator"><%= comment.body %></p>
-        <% elsif comment.user.official? && comment.user_id == @debate.author_id %>
+        <% elsif comment.user.official? && comment.user_id == @commentable.author_id %>
           <p class="comment-user level-<%= comment.user.official_level %> is-author"><%= comment.body %></p>
         <% elsif comment.user.official? %>
           <p class="comment-user level-<%= comment.user.official_level %>"><%= comment.body %></p>
-        <% elsif comment.user_id == @debate.author_id %>
+        <% elsif comment.user_id == @commentable.author_id %>
           <p class="comment-user is-author"><%= comment.body %></p>
         <% else %>
           <p class="comment-user"><%= comment.body %></p>
@@ -88,7 +88,7 @@
 
             <%= render 'comments/actions', comment: comment %>
 
-            <%= render 'comments/form', {commentable: @debate, parent_id: comment.id, toggeable: true} %>
+            <%= render 'comments/form', {commentable: @commentable, parent_id: comment.id, toggeable: true} %>
           <% end %>
         </div>
       </div>
diff --git a/app/views/comments/_form.html.erb b/app/views/comments/_form.html.erb
index 70e600df0..9a7d26554 100644
--- a/app/views/comments/_form.html.erb
+++ b/app/views/comments/_form.html.erb
@@ -1,8 +1,9 @@
-<div id="js-comment-form-<%= dom_id(commentable) %>" <%= "style='display:none'".html_safe if toggeable %>>
+<% css_id = parent_or_commentable_dom_id(parent_id, commentable) %>
+<div id="js-comment-form-<%= css_id %>" <%= "style='display:none'".html_safe if toggeable %>>
   <%= form_for [commentable, Comment.new], remote: true do |f| %>
-    <%= label_tag "comment-body-#{dom_id(commentable)}", t("comments.form.leave_comment") %>
-    <%= f.text_area :body, id: "comment-body-#{dom_id(commentable)}", label: false %>
-    <%= f.hidden_field :commentable_type, value: commentable.class %>
+    <%= label_tag "comment-body-#{css_id}", t("comments.form.leave_comment") %>
+    <%= f.text_area :body, id: "comment-body-#{css_id}", label: false %>
+    <%= f.hidden_field :commentable_type, value: commentable.class.name %>
     <%= f.hidden_field :commentable_id, value: commentable.id %>
     <%= f.hidden_field :parent_id, value: parent_id %>
 
@@ -10,14 +11,14 @@
 
     <% if can? :comment_as_moderator, commentable %>º
       <div class="right">
-        <%= f.check_box :as_moderator, id: "comment-as-moderator-#{dom_id(commentable)}", label: false %>
-        <%= label_tag "comment-as-moderator-#{dom_id(commentable)}", t("comments.form.comment_as_moderator"), class: "checkbox" %>
+        <%= f.check_box :as_moderator, id: "comment-as-moderator-#{css_id}", label: false %>
+        <%= label_tag "comment-as-moderator-#{css_id}", t("comments.form.comment_as_moderator"), class: "checkbox" %>
       </div>
     <% end %>
     <% if can? :comment_as_administrator, commentable %>
       <div class="right">
-        <%= f.check_box :as_administrator, id: "comment-as-administrator-#{dom_id(commentable)}",label: false %>
-        <%= label_tag "comment-as-administrator-#{dom_id(commentable)}", t("comments.form.comment_as_admin"), class: "checkbox" %>
+        <%= f.check_box :as_administrator, id: "comment-as-administrator-#{css_id}",label: false %>
+        <%= label_tag "comment-as-administrator-#{css_id}", t("comments.form.comment_as_admin"), class: "checkbox" %>
       </div>
     <% end %>
   <% end %>
diff --git a/app/views/comments/create.js.erb b/app/views/comments/create.js.erb
index ed3e9c8f9..ef2400172 100644
--- a/app/views/comments/create.js.erb
+++ b/app/views/comments/create.js.erb
@@ -1,10 +1,11 @@
-var parent_id = "<%= dom_id(@parent) %>";
 var comment_html = "<%= j(render @comment) %>"
 
-<% if @parent.is_a?(Debate) -%>
-  App.Comments.reset_form(parent_id);
-  App.Comments.add_comment(parent_id, comment_html);
+<% if @comment.root? -%>
+  var commentable_id = '<%= dom_id(@commentable) %>';
+  App.Comments.reset_form(commentable_id);
+  App.Comments.add_comment(commentable_id, comment_html);
 <% else -%>
+  var parent_id = '<%= "comment_#{@comment.parent_id}" %>';
   App.Comments.reset_and_hide_form(parent_id);
   App.Comments.add_reply(parent_id, comment_html);
 <% end -%>
diff --git a/app/views/comments/new.js.erb b/app/views/comments/new.js.erb
index 819686e72..963cdf16a 100644
--- a/app/views/comments/new.js.erb
+++ b/app/views/comments/new.js.erb
@@ -1,2 +1,5 @@
-var field_with_errors = "#js-comment-form-<%= dom_id(@parent) %> #comment-body-<%= dom_id(@parent) %>";
+<% dom_id = parent_or_commentable_dom_id(@comment.parent_id, @commentable) %>
+
+var field_with_errors = "#js-comment-form-<%= dom_id %> #comment-body-<%= dom_id %>";
 App.Comments.display_error(field_with_errors, "<%= j render('comments/errors') %>");
+
diff --git a/db/schema.rb b/db/schema.rb
index 8b8dd88e9..fb5abfd98 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -11,7 +11,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20150902114558) do
+ActiveRecord::Schema.define(version: 20150902120006) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -75,9 +75,6 @@ ActiveRecord::Schema.define(version: 20150902114558) do
     t.integer  "cached_votes_down",  default: 0
     t.datetime "confirmed_hide_at"
     t.string   "ancestry"
-    t.integer  "rgt"
-    t.integer  "lft"
-    t.integer  "parent_id"
   end
 
   add_index "comments", ["ancestry"], name: "index_comments_on_ancestry", using: :btree
diff --git a/spec/features/comments_spec.rb b/spec/features/comments_spec.rb
index c40863534..cb847e40e 100644
--- a/spec/features/comments_spec.rb
+++ b/spec/features/comments_spec.rb
@@ -124,8 +124,7 @@ feature 'Comments' do
     parent = create(:comment, commentable: debate)
 
     7.times do
-      create(:comment, commentable: debate).
-      move_to_child_of(parent)
+      create(:comment, commentable: debate, parent: parent)
       parent = parent.children.first
     end
 
diff --git a/spec/models/comment_spec.rb b/spec/models/comment_spec.rb
index 4115fedcf..dbb254063 100644
--- a/spec/models/comment_spec.rb
+++ b/spec/models/comment_spec.rb
@@ -25,24 +25,22 @@ describe Comment do
       parent = comment
 
       3.times do
-        create(:comment, commentable: debate).
-        move_to_child_of(parent)
+        create(:comment, commentable: debate, parent: parent)
         parent = parent.children.first
       end
 
       expect(comment.children_count).to eq(1)
-      expect(debate.comment_threads.count).to eq(4)
+      expect(debate.comments.count).to eq(4)
     end
 
     it "should increase children count" do
       expect do
-        create(:comment, commentable: debate).
-        move_to_child_of(comment)
+        create(:comment, commentable: debate, parent: comment)
       end.to change { comment.children_count }.from(0).to(1)
     end
 
     it "should decrease children count" do
-      new_comment = create(:comment, commentable: debate).move_to_child_of(comment)
+      new_comment = create(:comment, commentable: debate, parent: comment)
 
       expect { new_comment.destroy }.to change { comment.children_count }.from(1).to(0)
     end
diff --git a/spec/support/common_actions.rb b/spec/support/common_actions.rb
index b773ca269..d8b45ffc2 100644
--- a/spec/support/common_actions.rb
+++ b/spec/support/common_actions.rb
@@ -34,13 +34,14 @@ module CommonActions
   end
 
   def comment_on(debate)
-    user2 = create(:user)
+    user = create(:user)
 
-    login_as(user2)
+    login_as(user)
     visit debate_path(debate)
 
     fill_in "comment-body-debate_#{debate.id}", with: 'Have you thought about...?'
     click_button 'Publish comment'
+
     expect(page).to have_content 'Have you thought about...?'
   end