diff --git a/database/iso.dat b/database/iso.dat
index 5b2e20df..8558cd69 100644
--- a/database/iso.dat
+++ b/database/iso.dat
@@ -30,6 +30,7 @@ N(-3)        NH4+           0       N
 P            PO4-3          2.0     P               30.9738
 F            F-             0.0     F               18.9984
 Br           Br-            0.0     Br              79.904
+Alkalinity   CO2            0.0     50.05           50.05
 
 SOLUTION_SPECIES
 H3O+ = H3O+