diff --git a/src/hanoidb.erl b/src/hanoidb.erl
index aa1f1e2..e13a4e7 100644
--- a/src/hanoidb.erl
+++ b/src/hanoidb.erl
@@ -346,7 +346,6 @@ terminate(normal, _State) ->
     ok;
 terminate(_Reason, _State) ->
     error_logger:info_msg("got terminate(~p, ~p)~n", [_Reason, _State]),
-    % flush_nursery(State),
     ok.
 
 code_change(_OldVsn, State, _Extra) ->
@@ -386,11 +385,11 @@ handle_call({get, Key}, From, State=#state{ top=Top, nursery=Nursery } ) when is
             {noreply, State}
     end;
 
-handle_call(close, _From, State=#state{top=Top}) ->
+handle_call(close, _From, State=#state{ nursery=Nursery, top=Top, dir=Dir, max_level=MaxLevel, opt=Config }) ->
     try
-        {ok, State2} = flush_nursery(State),
+        ok = hanoidb_nursery:finish(Nursery, Top),
         ok = hanoidb_level:close(Top),
-        {stop, normal, ok, State2}
+        {stop, normal, ok, State#state{ nursery=hanoidb_nursery:new(Dir, MaxLevel, Config)}}
     catch
         E:R ->
             error_logger:info_msg("exception from close ~p:~p~n", [E,R]),
@@ -417,11 +416,6 @@ do_transact(TransactionSpec, State=#state{ nursery=Nursery, top=Top }) ->
     {ok, Nursery2} = hanoidb_nursery:transact(TransactionSpec, Nursery, Top),
     {ok, State#state{ nursery=Nursery2 }}.
 
-flush_nursery(State=#state{ nursery=Nursery, top=Top, dir=Dir, max_level=MaxLevel, opt=Config }) ->
-    ok = hanoidb_nursery:finish(Nursery, Top),
-    {ok, Nursery2} = hanoidb_nursery:new(Dir, MaxLevel, Config),
-    {ok, State#state{ nursery=Nursery2 }}.
-
 start_app() ->
     case application:start(?MODULE) of
         ok ->
diff --git a/src/hanoidb_nursery.erl b/src/hanoidb_nursery.erl
index a7eec4f..070861a 100644
--- a/src/hanoidb_nursery.erl
+++ b/src/hanoidb_nursery.erl
@@ -131,9 +131,9 @@ do_add(Nursery=#nursery{log_file=File, cache=Cache, total_size=TotalSize, count=
     ok = file:write(File, Data),
     Nursery1 = do_sync(File, Nursery),
 
-    {ok, Nursery2} =
-        do_inc_merge(Nursery1#nursery{ cache=Cache2, total_size=TotalSize+erlang:iolist_size(Data),
-                                       count=Count+1 }, 1, Top),
+    {ok, Nursery2} = do_inc_merge(Nursery1#nursery{ cache=Cache2,
+                                                    total_size=TotalSize + erlang:iolist_size(Data),
+                                                    count=Count + 1 }, 1, Top),
 
     if Count+1 >= ?BTREE_SIZE(?TOP_LEVEL) ->
             {full, Nursery2};
@@ -199,10 +199,10 @@ finish(#nursery{ dir=Dir, cache=Cache, log_file=LogFile,
             {ok, BT} = hanoidb_writer:open(BTreeFileName, [{size, ?BTREE_SIZE(?TOP_LEVEL)},
                                                            {compress, none} | Config]),
             try
-                [] = gb_trees_ext:fold(fun(Key, Value, Acc) ->
+                ok = gb_trees_ext:fold(fun(Key, Value, Acc) ->
                                                ok = hanoidb_writer:add(BT, Key, Value),
                                                Acc
-                                       end, [], Cache)
+                                       end, ok, Cache)
             after
                 ok = hanoidb_writer:close(BT)
             end,
@@ -286,18 +286,15 @@ transact(Spec, Nursery=#nursery{ log_file=File, cache=Cache0, total_size=TotalSi
 
     Count = gb_trees:size(Cache2),
 
-    do_inc_merge(Nursery2#nursery{ cache=Cache2, total_size=TotalSize+erlang:iolist_size(Data), count=Count },
-                 length(Spec), Top).
+    do_inc_merge(Nursery2#nursery{ cache=Cache2, total_size=TotalSize+erlang:iolist_size(Data), count=Count }, length(Spec), Top).
 
 do_inc_merge(Nursery=#nursery{ step=Step, merge_done=Done }, N, TopLevel) ->
     case Step+N >= ?INC_MERGE_STEP of
         true ->
-            io:format("do_inc_merge: true ~p ~p ~p~n", [Step, N, ?INC_MERGE_STEP]),
-            hanoidb_level:begin_incremental_merge(TopLevel, Step+N),
-            {ok, Nursery#nursery{ step=0, merge_done=Done+Step+N }};
+            hanoidb_level:begin_incremental_merge(TopLevel, Step + N),
+            {ok, Nursery#nursery{ step=0, merge_done=Done + Step + N }};
         false ->
-            io:format("do_inc_merge: false ~p ~p ~p~n", [Step, N, ?INC_MERGE_STEP]),
-            {ok, Nursery#nursery{ step=Step+N }}
+            {ok, Nursery#nursery{ step=Step + N }}
     end.
 
 do_level_fold(#nursery{cache=Cache}, FoldWorkerPID, KeyRange) ->
diff --git a/src/hanoidb_util.erl b/src/hanoidb_util.erl
index 5123994..3a53ff3 100644
--- a/src/hanoidb_util.erl
+++ b/src/hanoidb_util.erl
@@ -40,9 +40,7 @@
 -define(TAG_DELETED2, 16#85).
 -define(TAG_END,      16#FF).
 
--compile({inline, [
-                   crc_encapsulate/1, crc_encapsulate_kv_entry/2
-                  ]}).
+-compile({inline, [crc_encapsulate/1, crc_encapsulate_kv_entry/2 ]}).
 
 
 index_file_name(Name) ->
@@ -56,22 +54,22 @@ file_exists(FileName) ->
             false
     end.
 
-
-
-
-estimate_node_size_increment(_KVList,Key,Value) ->
-    byte_size(Key)
-        + 10
-        + if
-              is_integer(Value) ->
-                  5;
-              is_binary(Value) ->
-                  5 + byte_size(Value);
-              is_atom(Value) ->
-                  8;
-              is_tuple(Value) ->
-                  13
-          end.
+estimate_node_size_increment(_KVList, Key, {Value, _TStamp})
+  when is_integer(Value) -> byte_size(Key) + 5 + 4;
+estimate_node_size_increment(_KVList, Key, {Value, _TStamp})
+  when is_binary(Value) -> byte_size(Key) + 5 + 4 + byte_size(Value);
+estimate_node_size_increment(_KVList, Key, {Value, _TStamp})
+  when is_atom(Value) -> byte_size(Key) + 8 + 4;
+estimate_node_size_increment(_KVList, Key, {Value, _TStamp})
+  when is_tuple(Value) -> byte_size(Key) + 13 + 4;
+estimate_node_size_increment(_KVList, Key, Value)
+  when is_integer(Value) -> byte_size(Key) + 5 + 4;
+estimate_node_size_increment(_KVList, Key, Value)
+  when is_binary(Value) -> byte_size(Key) + 5 + 4 + byte_size(Value);
+estimate_node_size_increment(_KVList, Key, Value)
+  when is_atom(Value) -> byte_size(Key) + 8 + 4;
+estimate_node_size_increment(_KVList, Key, Value)
+  when is_tuple(Value) -> byte_size(Key) + 13 + 4.
 
 -define(NO_COMPRESSION, 0).
 -define(SNAPPY_COMPRESSION, 1).
diff --git a/src/hanoidb_writer.erl b/src/hanoidb_writer.erl
index 2bbcd84..a6d60f7 100644
--- a/src/hanoidb_writer.erl
+++ b/src/hanoidb_writer.erl
@@ -81,12 +81,12 @@ add(Ref, Key, Value) ->
 count(Ref) ->
     gen_server:call(Ref, count, infinity).
 
+%% @doc Close the btree index file
 close(Ref) ->
     gen_server:call(Ref, close, infinity).
 
 %%%
 
-
 init([Name, Options]) ->
     hanoidb_util:ensure_expiry(Options),
     Size = proplists:get_value(size, Options, 2048),
@@ -94,7 +94,7 @@ init([Name, Options]) ->
     case do_open(Name, Options, [exclusive]) of
         {ok, IdxFile} ->
             file:write(IdxFile, ?FILE_FORMAT),
-            BloomFilter = bloom:new(erlang:min(Size, 16#ffffffff), 0.001),
+            BloomFilter = bloom:new(erlang:min(Size, 16#ffffffff), 0.01),
             BlockSize = hanoidb:get_opt(block_size, Options, ?NODE_SIZE),
             {ok, #state{ name=Name,
                          index_file_pos=?FIRST_BLOCK_POS, index_file=IdxFile,
@@ -109,34 +109,39 @@ init([Name, Options]) ->
     end.
 
 
-handle_cast({add, Key, Value}, State)
-  when is_binary(Key), (is_binary(Value) orelse Value == ?TOMBSTONE)->
-    {ok, State2} = add_record(0, Key, Value, State),
+handle_cast({add, Key, {?TOMBSTONE, TStamp}}, State)
+  when is_binary(Key) ->
+    {ok, State2} = add_record(0, Key, {?TOMBSTONE, TStamp}, State),
+    {noreply, State2};
+handle_cast({add, Key, ?TOMBSTONE}, State)
+  when is_binary(Key) ->
+    {ok, State2} = add_record(0, Key, ?TOMBSTONE, State),
     {noreply, State2};
 handle_cast({add, Key, {Value, TStamp}}, State)
-  when is_binary(Key), (is_binary(Value) orelse Value == ?TOMBSTONE)->
+  when is_binary(Key), is_binary(Value) ->
     {ok, State2} = add_record(0, Key, {Value, TStamp}, State),
+    {noreply, State2};
+handle_cast({add, Key, Value}, State)
+  when is_binary(Key), is_binary(Value) ->
+    {ok, State2} = add_record(0, Key, Value, State),
     {noreply, State2}.
 
 handle_call(count, _From, State = #state{ value_count=VC, tombstone_count=TC }) ->
     {ok, VC+TC, State};
-
 handle_call(close, _From, State) ->
     {ok, State2} = flush_nodes(State),
-    {stop,normal,ok,State2}.
+    {stop, normal, ok, State2}.
 
-handle_info(Info,State) ->
+handle_info(Info, State) ->
     error_logger:error_msg("Unknown info ~p~n", [Info]),
-    {stop,bad_msg,State}.
-
+    {stop, bad_msg, State}.
 
 terminate(normal,_State) ->
     ok;
-
-%% premature delete -> cleanup
 terminate(_Reason, State) ->
-    file:close( State#state.index_file ),
-    file:delete( hanoidb_util:index_file_name(State#state.name) ).
+    %% premature delete -> cleanup
+    file:close(State#state.index_file),
+    file:delete(hanoidb_util:index_file_name(State#state.name)).
 
 code_change(_OldVsn, State, _Extra) ->
     {ok, State}.
@@ -174,7 +179,6 @@ do_open(Name, Options, OpenOpts) ->
 
 %% @doc flush pending nodes and write trailer
 flush_nodes(#state{ nodes=[], last_node_pos=LastNodePos, last_node_size=_LastNodeSize, bloom=Bloom }=State) ->
-
     BloomBin = term_to_binary(Bloom, [compressed]),
     BloomSize = byte_size(BloomBin),
 
@@ -213,7 +217,8 @@ add_record(Level, Key, Value,
 
     %% Assert that keys are increasing:
     case List of
-        [] -> ok;
+        [] ->
+            ok;
         [{PrevKey,_}|_] ->
             if
                 (Key >= PrevKey) -> ok;