diff --git a/rowers/dataprep.py b/rowers/dataprep.py
index 25f02385..b5f74f84 100644
--- a/rowers/dataprep.py
+++ b/rowers/dataprep.py
@@ -379,6 +379,7 @@ def clean_df_stats(datadf, workstrokesonly=True, ignorehr=True,
         pass
 
     datadf.replace(to_replace=0, value=np.nan, inplace=True)
+    #    datadf = datadf.map_partitions(lambda df:df.replace(to_replace=0,value=np.nan))
 
     # bring spm back to real values
     try:
@@ -406,55 +407,55 @@ def clean_df_stats(datadf, workstrokesonly=True, ignorehr=True,
     if not ignorehr:
         try:
             mask = datadf['hr'] < 30
-            datadf.loc[mask, 'hr'] = np.nan
+            datadf.mask(mask,inplace=True)
         except KeyError:
             pass
 
     try:
         mask = datadf['spm'] < 0
-        datadf.loc[mask,'spm'] = np.nan
+        datadf.mask(mask,inplace=True)
     except KeyError:
         pass
         
     try:
         mask = datadf['efficiency'] > 200.
-        datadf.loc[mask, 'efficiency'] = np.nan
+        datadf.mask(mask,inplace=True)
     except KeyError:
         pass
         
     try:
         mask = datadf['spm'] < 10
-        datadf.loc[mask, 'spm'] = np.nan
+        datadf.mask(mask,inplace=True)
     except KeyError:
         pass
 
 
     try:
         mask = datadf['pace'] / 1000. > 300.
-        datadf.loc[mask, 'pace'] = np.nan
+        datadf.mask(mask,inplace=True)
     except KeyError:
         pass
 
     try:
         mask = datadf['efficiency'] < 0.
-        datadf.loc[mask, 'efficiency'] = np.nan
+        datadf.mask(mask,inplace=True)
     except KeyError:
         pass
 
     try:
         mask = datadf['pace'] / 1000. < 60.
-        datadf.loc[mask, 'pace'] = np.nan
+        datadf.mask(mask,inplace=True)
     except KeyError:
         pass
 
     try:
         mask = datadf['spm'] > 60
-        datadf.loc[mask, 'spm'] = np.nan
+        datadf.mask(mask,inplace=True)
     except KeyError:
         pass
 
     try:
-        mask = datadf['wash'] < 1
+        mask = datadf['wash'] > 1
         datadf.loc[mask, 'wash'] = np.nan
     except KeyError:
         pass
@@ -462,67 +463,67 @@ def clean_df_stats(datadf, workstrokesonly=True, ignorehr=True,
     if not ignoreadvanced:
         try:
             mask = datadf['rhythm'] < 5
-            datadf.loc[mask, 'rhythm'] = np.nan
+            datadf.mask(mask,inplace=True)
         except KeyError:
             pass
 
         try:
             mask = datadf['rhythm'] > 70
-            datadf.loc[mask, 'rhythm'] = np.nan
+            datadf.mask(mask,inplace=True)
         except KeyError:
             pass
 
         try:
             mask = datadf['power'] < 20
-            datadf.loc[mask, 'power'] = np.nan
+            datadf.mask(mask,inplace=True)
         except KeyError:
             pass
 
         try:
             mask = datadf['drivelength'] < 0.5
-            datadf.loc[mask, 'drivelength'] = np.nan
+            datadf.mask(mask,inplace=True)
         except KeyError:
             pass
 
         try:
             mask = datadf['forceratio'] < 0.2
-            datadf.loc[mask, 'forceratio'] = np.nan
+            datadf.mask(mask,inplace=True)
         except KeyError:
             pass
 
         try:
             mask = datadf['forceratio'] > 1.0
-            datadf.loc[mask, 'forceratio'] = np.nan
+            datadf.mask(mask,inplace=True)
         except KeyError:
             pass
 
         try:
             mask = datadf['drivespeed'] < 0.5
-            datadf.loc[mask, 'drivespeed'] = np.nan
+            datadf.mask(mask,inplace=True)
         except KeyError:
             pass
 
         try:
             mask = datadf['drivespeed'] > 4
-            datadf.loc[mask, 'drivespeed'] = np.nan
+            datadf.mask(mask,inplace=True)
         except KeyError:
             pass
 
         try:
             mask = datadf['driveenergy'] > 2000
-            datadf.loc[mask, 'driveenergy'] = np.nan
+            datadf.mask(mask,inplace=True)
         except KeyError:
             pass
 
         try:
             mask = datadf['driveenergy'] < 100
-            datadf.loc[mask, 'driveenergy'] = np.nan
+            datadf.mask(mask,inplace=True)
         except KeyError:
             pass
 
         try:
             mask = datadf['catch'] > -30.
-            datadf.loc[mask, 'catch'] = np.nan
+            datadf.mask(mask,inplace=True)
         except KeyError:
             pass
 
@@ -1772,7 +1773,7 @@ def getrowdata_db(id=0, doclean=False, convertnewtons=True,
 
 # Fetch a subset of the data from the DB
 
-def getsmallrowdata_db(columns, ids=[], doclean=True,workstrokesonly=True):
+def getsmallrowdata_db(columns, ids=[], doclean=True,workstrokesonly=True,compute=True):
     prepmultipledata(ids)
 
     csvfilenames = ['media/strokedata_{id}.parquet'.format(id=id) for id in ids]
@@ -1792,16 +1793,19 @@ def getsmallrowdata_db(columns, ids=[], doclean=True,workstrokesonly=True):
     else:
         df = dd.read_parquet(csvfilenames[0],columns=columns,engine='pyarrow')
 
-    data = df.compute()
-    data = data.loc[:,~data.columns.duplicated()]
-    extracols = []
-    if doclean:
-        data = clean_df_stats(data, ignorehr=True,
-                              workstrokesonly=workstrokesonly)
+    df = df.loc[:,~df.columns.duplicated()]
+
+
+    if compute:
+        data = df.compute()
+        if doclean:
+            data = clean_df_stats(data, ignorehr=True,
+                                workstrokesonly=workstrokesonly)
         data.dropna(axis=1,how='all',inplace=True)
         data.dropna(axis=0,how='any',inplace=True)
-
-    return data
+        return data
+    
+    return df
 
 def getsmallrowdata_db_old(columns, ids=[], doclean=True, workstrokesonly=True):
     prepmultipledata(ids)
diff --git a/rowers/dataprepnodjango.py b/rowers/dataprepnodjango.py
index a2ac7764..3347ac49 100644
--- a/rowers/dataprepnodjango.py
+++ b/rowers/dataprepnodjango.py
@@ -16,6 +16,8 @@ from pandas import DataFrame,Series
 import pandas as pd
 import numpy as np
 import itertools
+import dask.dataframe as dd
+from dask.delayed import delayed
 
 from sqlalchemy import create_engine
 import sqlalchemy as sa