diff --git a/src/dexorder/blockstate/state.py b/src/dexorder/blockstate/state.py
index 1e0a2d9..2dff20b 100644
--- a/src/dexorder/blockstate/state.py
+++ b/src/dexorder/blockstate/state.py
@@ -198,7 +198,10 @@ class BlockState:
                     else:
                         updated_keys.add((d.series, d.key))
                 del self.diffs_by_hash[dead.hash]
-            del self.ancestors[dead.hash]
+            try:
+                del self.ancestors[dead.hash]
+            except KeyError:
+                pass # todo is this bad?
 
         # prune diffs_by_series by removing old series diffs that have been superceded by new diffs
         for s, k in updated_keys:
diff --git a/src/dexorder/ohlc.py b/src/dexorder/ohlc.py
index f7f088a..9c937f6 100644
--- a/src/dexorder/ohlc.py
+++ b/src/dexorder/ohlc.py
@@ -1,7 +1,6 @@
 import json
 import logging
 import os
-from dataclasses import dataclass
 from datetime import datetime, timedelta, timezone
 from typing import Optional, NamedTuple, Reversible, Union
 
@@ -35,27 +34,63 @@ def opt_dec(v):
 def dt(v):
     return v if isinstance(v, datetime) else from_timestamp(v)
 
-@dataclass
 class NativeOHLC:
     @staticmethod
     def from_ohlc(ohlc: OHLC) -> 'NativeOHLC':
-        return NativeOHLC(*[cast(value) for value, cast in zip(ohlc,(dt, opt_dec, opt_dec, opt_dec, dec))])
+        return NativeOHLC(*[cast(value) for value, cast in zip(ohlc,(dt, opt_dec, opt_dec, opt_dec, dec))], ohlc=ohlc)
+
+    # noinspection PyShadowingBuiltins
+    def __init__(self, start: datetime, open: Optional[dec], high: Optional[dec], low: Optional[dec], close: dec,
+                 *, ohlc: list=None):
+        self.start = start
+        self.open = open
+        self.high = high
+        self.low = low
+        self.close = close
+        self._ohlc = ohlc  # JSON-able representation
+        self._json: str = None if ohlc is None else json.dumps(ohlc)
+
+
+    def update(self, price):
+        pstr = str(price)
+        if self.open is None:
+            self.open = price
+            self.high = price
+            self.low = price
+            if self._ohlc:
+                self._ohlc[1] = pstr
+                self._ohlc[2] = pstr
+                self._ohlc[3] = pstr
+        else:
+            self.high = max(self.high, price)
+            self.low = min(self.low, price)
+            if self._ohlc:
+                self._ohlc[1] = str(self.high)
+                self._ohlc[2] = str(self.low)
+        self.close = price
+        if self._ohlc:
+            self._ohlc[3] = pstr
+        self._json = None
 
-    start: datetime
-    open: Optional[dec]
-    high: Optional[dec]
-    low: Optional[dec]
-    close: dec
 
     @property
     def ohlc(self) -> OHLC:
-        return [
-            timestamp(self.start),
-            None if self.open is None else str(self.open),
-            None if self.high is None else str(self.high),
-            None if self.low is None else str(self.low),
-            str(self.close)
-        ]
+        if self._ohlc is None:
+            self._ohlc = [
+                timestamp(self.start),
+                None if self.open is None else str(self.open),
+                None if self.high is None else str(self.high),
+                None if self.low is None else str(self.low),
+                str(self.close)
+            ]
+        return self._ohlc
+
+
+    @property
+    def json(self) -> str:
+        if self._json is None:
+            self._json = json.dumps(self.ohlc)
+        return self._json
 
 
 def period_name(period: timedelta) -> str:
@@ -79,13 +114,13 @@ def ohlc_start_time(time, period: timedelta):
     return OHLC_DATE_ROOT + timedelta(seconds=period_sec * period_count)
 
 
-def update_ohlc(prev: OHLC, period: timedelta, time: datetime, price: Optional[dec]) -> list[OHLC]:
+def update_ohlc(prev: NativeOHLC, period: timedelta, time: datetime, price: Optional[dec]) -> list[NativeOHLC]:
     """
     returns an ordered list of OHLC's that have been created/modified by the new time/price
     if price is None, then bars are advanced based on the time but no new price is added to the series.
     """
     # log.debug(f'\tupdating {prev} with {minutely(time)} {price}')
-    cur = NativeOHLC.from_ohlc(prev)
+    cur = prev
     assert time >= cur.start
     result = []
     # advance time and finalize any past OHLC's into the result array
@@ -93,20 +128,13 @@ def update_ohlc(prev: OHLC, period: timedelta, time: datetime, price: Optional[d
         end = cur.start + period
         if time < end:
             break
-        result.append(cur.ohlc)
+        result.append(cur)
         cur = NativeOHLC(end, None, None, None, cur.close)
     # log.debug(f'\ttime advancements: {result}')
     # if we are setting a price, update the current bar
     if price is not None:
-        if cur.open is None:
-            cur.open = price
-            cur.high = price
-            cur.low = price
-        else:
-            cur.high = max(cur.high, price)
-            cur.low = min(cur.low, price)
-        cur.close = price
-    result.append(cur.ohlc)
+        cur.update(price)
+    result.append(cur)
     # log.debug(f'\tappended current bar: {cur.ohlc}')
     # log.debug(f'\tupdate result: {result}')
     return result
@@ -116,13 +144,85 @@ class OHLCKey (NamedTuple):
     period: timedelta
 
 
+def chunk_path(symbol: str, period: timedelta, time: datetime, *, chain_id: int = None) -> str:
+    if chain_id is None:
+        chain_id = current_chain.get().chain_id
+    start = ohlc_start_time(time, period)
+    name = period_name(period)
+    return f'{chain_id}/{symbol}/{name}/' + (
+        f'{start.year}/{symbol}-{name}-{start:%Y%m%d}.json' if period < timedelta(hours=1) else  # <1H data has a file per day
+        f'{start.year}/{symbol}-{name}-{start:%Y%m}.json' if period < timedelta(days=7) else  # <1W data has a file per month
+        f'{symbol}-{name}.json'  # long periods are a single file for all of history
+    )
+
+
+class Chunk:
+    """ Chunks map to files of OHLC's on disk """
+    def __init__(self, repo_dir: str, symbol: str, period: timedelta, time: datetime,
+                 *, bars: Optional[list[NativeOHLC]] = None, chain_id: int = None):
+        self.repo_dir = repo_dir
+        self.symbol = symbol
+        self.period = period
+        self.chain_id = chain_id if chain_id is not None else current_chain.get().chain_id
+        self.path = chunk_path(symbol, period, time, chain_id=chain_id)
+        self.fullpath = os.path.join(repo_dir, self.path)
+        if bars is not None:
+            self.bars = bars
+        else:
+            try:
+                with open(self.fullpath, 'r') as file:
+                    bars = json.load(file)
+                self.bars = [NativeOHLC.from_ohlc(ohlc) for ohlc in bars]
+            except FileNotFoundError:
+                self.bars = []
+
+
+    def update(self, native: NativeOHLC):
+        if not self.bars:
+            self.bars = [native]
+            return
+        start = self.bars[0].start
+        index = (native.start - start) // self.period
+        # log.debug(f'save {symbol} {ohlc_name(period)} chunk {start} index {index} <= {len(chunk)}')
+        if index > len(self.bars):
+            log.error(f'chunk gap: {index} > {len(self.bars)} {self.symbol} {period_name(self.period)} {native}' + ''.join(
+                f'\n\t{c}' for c in self.bars))
+            exit(1)
+        if index == len(self.bars):
+            assert self.bars[-1].start + self.period == native.start
+            self.bars.append(native)
+        else:
+            assert self.bars[index].start == native.start
+            self.bars[index] = native
+
+
+    def save(self):
+        for _ in range(2):
+            try:
+                with open(self.fullpath, 'w') as file:
+                    json.dump([n.ohlc for n in self.bars], file)
+                return
+            except FileNotFoundError:
+                os.makedirs(os.path.dirname(self.fullpath), exist_ok=True)
+        raise IOError(f'Could not write chunk {self.fullpath}')
+
+
+    def __eq__(self, other):
+        return self.path == other.path
+
+
+    def __hash__(self):
+        return hash(self.path)
+
+
 class OHLCRepository:
     def __init__(self, base_dir: str = None):
         """ can't actually make more than one of these because there's a global recent_ohlcs BlockDict """
         if base_dir is None:
             base_dir = config.ohlc_dir
         self.dir = base_dir
-        self.cache = LFUCache(len(OHLC_PERIODS) * 128)  # enough for the top 128 pools
+        self.cache = LFUCache(len(OHLC_PERIODS) * 1024)
+        self.dirty_chunks = set()
 
     @staticmethod
     def add_symbol(symbol: str, period: timedelta = None):
@@ -139,28 +239,30 @@ class OHLCRepository:
             self.update(symbol, period, time, price, create=create)
 
     @staticmethod
-    def update(symbol: str, period: timedelta, time: datetime, price: Optional[dec] = None, *, create: bool = True) -> Optional[list[OHLC]]:
+    def update(symbol: str, period: timedelta, time: datetime, price: Optional[dec] = None, *, create: bool = True) \
+            -> Optional[list[NativeOHLC]]:
         """
         if price is None, then bars are advanced based on the time but no new price is added to the series.
         """
         logname = f'{symbol} {period_name(period)}'
         # log.debug(f'Updating OHLC {logname} {minutely(time)} {price}')
-        key = (symbol, period)
-        # bars is a list of "recent" OHLC's stored as blockdata.  we try to keep the recent array long enough to extend before the root block time
-        historical: Optional[list[OHLC]] = recent_ohlcs.get(key)
+        key = symbol, period
+        # recent_ohlcs holds a list of "recent" NativeOHLC's stored as blockdata.  we try to keep the recent array long
+        # enough to extend prior the root block time
+        historical: Optional[list[NativeOHLC]] = recent_ohlcs.get(key)
         # log.debug(f'got recent {historical}')
         if not historical:
             if create is False or price is None:
                 return  # do not track symbols which have not been explicity set up
-            p = str(price)
             historical = []
-            updated = [OHLC((timestamp(ohlc_start_time(time, period)), p, p, p, p))]
+            updated = [NativeOHLC(ohlc_start_time(time, period), price, price, price, price)]
             # log.debug(f'\tcreated new bars {updated}')
         else:
             updated = update_ohlc(historical[-1], period, time, price)
             # drop any historical bars that are older than we need
-            oldest_needed = from_timestamp(current_blockstate.get().root_block.timestamp) - period  # cover the root block time plus one period prior
-            trim = (oldest_needed - from_timestamp(historical[0][0])) // period
+            # oldest_needed = cover the root block time plus one period prior
+            oldest_needed = from_timestamp(current_blockstate.get().root_block.timestamp) - period
+            trim = (oldest_needed - historical[0].start) // period
             if trim > 0:
                 historical = historical[trim:]
 
@@ -168,118 +270,89 @@ class OHLCRepository:
         if not historical or not updated:
             updated = historical + updated
         else:
-            last_bar = from_timestamp(historical[-1][0])
-            first_updated = from_timestamp(updated[0][0])
+            last_bar = historical[-1].start
+            first_updated = updated[0].start
             overlap = (first_updated - last_bar) // period + 1
             updated = historical[:-overlap] + updated if overlap > 0 else historical + updated
         # log.debug(f'\tnew recents: {updated}')
         recent_ohlcs.setitem(key, updated)
         return updated
 
-    def save_all(self, symbol: str, period: timedelta, ohlc_list: list[OHLC]) -> None:
+    def save_all(self, symbol: str, period: timedelta, ohlc_list: list[NativeOHLC]) -> None:
+        """ saves all OHLC's in the list """
         for ohlc in ohlc_list:
-            self.save(symbol, period, ohlc)  # we need to act synchronously so we don't have conflicting access to chunks
+            self.save(symbol, period, ohlc)
 
-    def save(self, symbol: str, period: timedelta, ohlc: OHLC) -> None:
+    def save(self, symbol: str, period: timedelta, native: NativeOHLC) -> None:
+        """
+        pushes the native OHLC to a Chunk but DOES NOT WRITE TO DISK YET.  you must call flush() to write all
+        dirty chunks to disk after a batch of OHLC's has been saved.
+        """
         # log.debug(f'saving ohlc {symbol} {period_name(period)} {ohlc}')
-        time = dt(ohlc[0])
-        chunk = self.get_chunk(symbol, period, time)
+        chunk = self.get_chunk(symbol, period, native.start)
         if not chunk:
-            chunk = [ohlc]
+            chunk = self.cache[chunk.path] = Chunk(self.dir, symbol, period, native.start, bars=[native])
         else:
-            start = from_timestamp(chunk[0][0])
-            index = (time - start) // period
-            # log.debug(f'save {symbol} {ohlc_name(period)} chunk {start} index {index} <= {len(chunk)}')
-            if index > len(chunk):
-                log.error(f'chunk gap: {index} > {len(chunk)} {symbol} {period_name(period)} {ohlc}'+''.join(f'\n\t{c}' for c in chunk))
-                exit(1)
-            if index == len(chunk):
-                assert from_timestamp(chunk[-1][0]) + period == time
-                chunk.append(ohlc)
-            else:
-                assert from_timestamp(chunk[index][0]) == time
-                chunk[index] = ohlc
-        self.save_chunk(symbol, period, chunk)
+            chunk.update(native)
+        self.dirty_chunks.add(chunk)
 
-    def get_chunk(self, symbol: str, period: timedelta, start_time: datetime) -> list[OHLC]:
-        path = self.chunk_path(symbol, period, start_time)
-        found = self.cache.get(path)
+    def get_chunk(self, symbol: str, period: timedelta, time: datetime) -> Chunk:
+        start_time = ohlc_start_time(time, period)
+        chain_id = current_chain.get().chain_id
+        key = chunk_path(symbol, period, time, chain_id=chain_id)
+        found = self.cache.get(key)
         if found is None:
-            found = self.load_chunk(path)
-            if found is None:
-                found = []
-            self.cache[path] = found
+            found = self.cache[key] = Chunk(self.dir, symbol, period, start_time, chain_id=chain_id)
         return found
 
-    @staticmethod
-    def load_chunk(path: str) -> Optional[list[OHLC]]:
-        try:
-            with open(path, 'r') as file:
-                return json.load(file)
-        except FileNotFoundError:
-            return []
-        except:
-            log.error(f'exception loading chunk {path}')
-            raise
-
-    def save_chunk(self, symbol: str, period: timedelta, chunk: list[OHLC]):
-        if not chunk:
-            return
-        path = self.chunk_path(symbol, period, from_timestamp(chunk[0][0]))
-        for _ in range(2):
-            try:
-                with open(path, 'w') as file:
-                    json.dump(chunk, file)
-                self.cache[path] = chunk
-                return
-            except FileNotFoundError:
-                os.makedirs(os.path.dirname(path), exist_ok=True)
-        raise IOError(f'Could not write chunk {path}')
+    def flush(self) -> None:
+        for chunk in self.dirty_chunks:
+            chunk.save()
+        self.dirty_chunks.clear()
 
 
-    def chunk_path(self, symbol: str, period: timedelta, time: datetime, *, chain_id: int = None) -> str:
-        if chain_id is None:
-            chain_id = current_chain.get().chain_id
-        start = ohlc_start_time(time, period)
-        name = period_name(period)
-        return f'{self.dir}/{chain_id}/{symbol}/{name}/' + (
-            f'{start.year}/{symbol}-{name}-{start:%Y%m%d}.json' if period < timedelta(hours=1) else  # <1H data has a file per day
-            f'{start.year}/{symbol}-{name}-{start:%Y%m}.json' if period < timedelta(days=7) else  # <1W data has a file per month
-            f'{symbol}-{name}.json'  # long periods are a single file for all of history
-        )
-
-
-def pub_ohlc(_series:str, key: OHLCKey, bars: list[OHLC]):
+def pub_ohlc(_series:str, key: OHLCKey, bars: list[NativeOHLC]):
     pool_addr, period = key
     chain_id = current_chain.get().chain_id
     return (
         f'{chain_id}|{pool_addr}|{period_name(period)}',  # channel name is like 0x...|1m
         'ohlcs',
-        (chain_id, pool_addr, bars)
+        (chain_id, pool_addr, [b.ohlc for b in bars])
     )
 
 def ohlc_key_to_str(k):
     return f'{k[0]}|{period_name(k[1])}'
 
 def ohlc_str_to_key(s):
-    pool, period_name = s.split('|')
-    return pool, period_from_name(period_name)
+    pool, period = s.split('|')
+    return pool, period_from_name(period)
 
 def ohlc_save(_block: Block, diffs: Reversible[Union[DiffItem, DiffEntryItem]]):
     """
     used as a finalization callback from BlockState data.
     """
+    dirty = False
     for diff in diffs:
         if diff.series == 'ohlc':
             symbol, period = diff.key
             ohlcs.save_all(symbol, period, diff.value)
+            dirty = True
+    if dirty:
+        ohlcs.flush()
 
+def ohlc_value_to_string(bars: list[NativeOHLC]):
+    return '['+','.join(b.json for b in bars)+']'
+
+def ohlc_value_from_string(s: str):
+    return [NativeOHLC.from_ohlc(ohlc) for ohlc in json.loads(s)]
 
 # The most recent OHLC's are stored as block data.  We store a list of at least the two latest bars, which provides clients with
 # the latest finalized bar as well as the current open bar.
-recent_ohlcs: BlockDict[OHLCKey, list[OHLC]] = BlockDict('ohlc', db=True, redis=True, pub=pub_ohlc,
-                                                         key2str=ohlc_key_to_str, str2key=ohlc_str_to_key,
-                                                         series2key=lambda x:x, series2str=lambda x:x)
+recent_ohlcs: BlockDict[OHLCKey, list[NativeOHLC]] = BlockDict(
+    'ohlc', db=True, redis=True, pub=pub_ohlc,
+    key2str=ohlc_key_to_str, str2key=ohlc_str_to_key, series2key=lambda x: x, series2str=lambda x: x,
+    value2str=ohlc_value_to_string, str2value=ohlc_value_from_string
+)
 
 
 ohlcs = OHLCRepository()
diff --git a/src/dexorder/pools.py b/src/dexorder/pools.py
index 767f5fd..a7c7a3d 100644
--- a/src/dexorder/pools.py
+++ b/src/dexorder/pools.py
@@ -73,7 +73,7 @@ async def uniswap_price(pool: PoolDict, sqrt_price=None) -> dec:
     pool_dec = pool['decimals']
     price = dec(sqrt_price*sqrt_price) / 2 ** (96 * 2)
     result = price * dec(10) ** dec(pool_dec)
-    log.debug(f'pool sqrtX96 {sqrt_price} with {pool_dec} decimals = {result}')
+    # log.debug(f'pool sqrtX96 {sqrt_price} with {pool_dec} decimals = {result}')
     return result