diff --git a/src/dexorder/final_ohlc.py b/src/dexorder/final_ohlc.py
index bd4d9ef..2a3c247 100644
--- a/src/dexorder/final_ohlc.py
+++ b/src/dexorder/final_ohlc.py
@@ -150,6 +150,7 @@ class OHLCFile:
         # first we write the "final" rows which means rows that have been closed and will get no more data.
         for row in self._final_rows:
             self.file.write(OHLCFile.row_bytes(row))
+        self._final_rows.clear()
         # apply any pending changes to the current row
         if self._pending is not None:
             self._cur = self._pending
@@ -214,19 +215,25 @@ class OHLCFileSeries:
         self.base_dir = base_dir
         self.symbol = symbol
         self.series_start: Optional[datetime] = None  # timestamp of the first datum in the series
-        self.write_offset: int = 0
+        self.write_offset: Optional[int] = None
         self.last_flush: Optional[tuple[datetime,dec]] = None
         self.quote_file = None
         self.dirty_files = set()
         self.quote: Optional[tuple[datetime,dec]] = None
 
+
+    @property
+    def quote_filename(self):
+        return os.path.join(self.base_dir, self.symbol, 'quote.csv')
+
+
     def update(self, time: datetime, price: dec):
         #
         # load quote file
         #
         if self.quote_file is None:
 
-            quote_filename = os.path.join(self.base_dir, self.symbol, 'quote.csv')
+            quote_filename = self.quote_filename
             try:
                 self.quote_file = open(quote_filename, 'br+')
                 # load existing quote file
@@ -289,14 +296,28 @@ class OHLCFileSeries:
         #
         # flush quote file
         #
-        self.quote_file.write(f'{ts},{price:f}'.encode('ascii'))
-        self.quote_file.flush()
-        self.quote_file.seek(self.write_offset)
+        try:
+            start_of_column = self.quote_file.tell()
+            self.quote_file.write(f'{ts},{price:f}'.encode('ascii'))
+            self.quote_file.truncate()
+            self.quote_file.flush()
+            self.quote_file.seek(start_of_column)
+        except IOError:
+            log.exception(f'While saving quote file {self.quote_filename}')
 
-        # remember where we were so we can forward-fill again next time
+        # remember the last flush point so we can forward-fill next time
         self.last_flush = self.quote
 
 
+    def __hash__(self):
+        return hash((self.base_dir,self.symbol))
+
+
+    def __eq__(self, other):
+        return other.base_dir == self.base_dir and other.symbol == self.symbol
+
+
+
 class FinalOHLCRepository:
     """
     Used for backfill when all data is known to be final. Keeps a simple table of current NativeOHLC candles.