I just found out the actual reaction in the lab for the CO2.
Well almost anyways.
Cirtic Acid + Bicarbonate = CO2 + H20 + Na(citrate).
So the water dissolves the tablet, since the material do not react in dry form. Once dissolved the material in the tablet react with each other.
HCO3-1 + H+ ------------> H2O(l) + CO2(g)
and CO3-2 + 2 H+ -----------> H2O(l) + CO2(g)
So having excess Na+ in the sysem from the salt should SLOW the reaction.
But how the Ca+2 affects it is unknown to me at this moment.
ADDED: The salts act as catalysts to the sytems, so in your data
NaCl + H20 should have a faster rate than just H2O
CaCl2 + H2O should have a faster rate than just H2O
Though I haven't figured out exaclty how.....Geodome is probably right w.r.t. the catalysis.
HOPE THIS HELPS