diff --git a/aosstower/schema.py b/aosstower/schema.py
index 18bffa23300d79cde6e1a13d1ffe871222b18ae0..f03f7c093223c5e0da490c8bce68d787a90733ea 100644
--- a/aosstower/schema.py
+++ b/aosstower/schema.py
@@ -12,9 +12,9 @@ database = dict(
         'box_temp',
         'Auxillary Temperature',
         'degC',
-        '',
-        '',
-        '',
+        None,
+        None,
+        None,
         ),
     box_pressure=Var(
         float32,
@@ -24,37 +24,37 @@ database = dict(
         'hPa',
         '850',
         '1100',
-        '',
+        None,
     ),
     paro_air_temp_period=Var(
         float32,
-        '',
+        None,
         'paro_air_temp_period',
-        '',
+        None,
         '1',
-        '',
-        '',
-        '',
+        None,
+        None,
+        None,
         ),
     paro_pressure_period=Var(
         float32,
-        '',
+        None,
         'paro_pressure_period',
-        '',
+        None,
         '1',
-        '',
-        '',
-        '',
+        None,
+        None,
+        None,
     ),
     paro_air_temp=Var(
         float32,
         'air_temperature',
         'paro_air_temp',
-        '',
+        None,
         'degC',
         '-50', 
         '50',
-        '',
+        None,
         ),
     pressure=Var(
         float32,
@@ -64,17 +64,17 @@ database = dict(
         'hPa',
         '850',
         '1100',
-        '',
+        None,
         ),
     paro_cal_sig=Var(
         float32,
-        '',
+        None,
         'paro_cal_sig',
-        '',
-        '',
-        '',
-        '',
-        '',
+        None,
+        None,
+        None,
+        None,
+        None,
         ),
     box_rh=Var(
         float32,
@@ -84,7 +84,7 @@ database = dict(
         '%',
         '0',
         '100',
-        '',
+        None,
         ),
     box_air_temp=Var(
         float32,
@@ -94,7 +94,7 @@ database = dict(
         'degC',
         '-50',
         '50',
-        '',
+        None,
         ),
     air_temp_2=Var(
         float32,
@@ -104,7 +104,7 @@ database = dict(
         'degC',
         '-50',
         '50',
-        '',
+        None,
         ),
     air_temp_3=Var(
         float32,
@@ -114,7 +114,7 @@ database = dict(
         'degC',
         '-50',
         '50',
-        '',
+        None,
         ),
     air_temp_4=Var(
         float32,
@@ -124,7 +124,7 @@ database = dict(
         'degC',
         '-50',
         '50',
-        '',
+        None,
         ),
     air_temp_5=Var(
         float32,
@@ -134,7 +134,7 @@ database = dict(
         'degC',
         '-50',
         '50',
-        '',
+        None,
         ),
     wind_speed=Var(
         float32,
@@ -144,7 +144,7 @@ database = dict(
         'm*s^-1',
         '0',
         '50',
-        '',
+        None,
         ),
     wind_dir=Var(
         float32,
@@ -154,17 +154,17 @@ database = dict(
         'degrees',
         '0',
         '360',
-        '',
+        None,
         ),
     rh_shield_freq=Var(
         float32,
-        '',
+        None,
         'rh_shield_freq',
-        '',
+        None,
         'hz',
-        '',
-        '',
-        '',
+        None,
+        None,
+        None,
         ),
     rh=Var(
         float32,
@@ -174,7 +174,7 @@ database = dict(
         '%',
         '0',
         '100',
-        '',
+        None,
         ),
     air_temp_6_3m=Var(
         float32,
@@ -184,7 +184,7 @@ database = dict(
         'degC',
         '-50',
         '50',
-        '',
+        None,
         ),
     dewpoint=Var(
         float32,
@@ -194,17 +194,17 @@ database = dict(
         'degC',
         '-50',
         '50',
-        '',
+        None,
     ),
     rtd_shield_freq=Var(
         float32,
-        '',
+        None,
         'rtd_shied_freq',
-        '',
-        '',
-        '',
-        '',
-        '',
+        None,
+        None,
+        None,
+        None,
+        None,
         ),
     air_temp=Var(
         float32,
@@ -214,7 +214,7 @@ database = dict(
         'degC',
         '-50',
         '50',
-        '',
+        None,
         ),
     solar_flux=Var(
         float32,
@@ -224,17 +224,17 @@ database = dict(
         'w*m^-2',
         '0',
         '3000',
-        '',
+        None,
     ),
     precip=Var(
         float32,
-        '',
+        None,
         'precip',
         'Precipitation',
         'mm',
         '0',
         '254',
-        '',
+        None,
         ),
     accum_precip=Var(
         float32,
@@ -244,17 +244,17 @@ database = dict(
         'mm',
         '0',
         '254',
-        '',
+        None,
         ),
     altimeter=Var(
         float32,
-        '',
+        None,
         'altimeter',
-        '',
+        None,
         'inHg',
-        '',
-        '',
-        '',
+        None,
+        None,
+        None,
         ),
     gust=Var(
         float32,
@@ -264,7 +264,7 @@ database = dict(
         'm/s',
         '0',
         '50',
-        '',
+        None,
     )
 )