OK, offhand I can't say whether 300F is actually hot enough, but the reaction would be:
2 NaHCO3 (s) --> Na2CO3(s) + H2O(g) + CO2(g)
As to the amount, it would take half as much to raise the pH the same amount as baking soda - since the carbonate ion will accept a proton to become the bicarbonate ion. Remember that saltwater folks are trying to achieve/maintain a pH>8, so this is one way to do it.
72g bowfront planted, CO2, 4x - T5HO, Eheim 2213 and 2217, 2 angels, pristella tetras, blue tetras, betta, albino bristlenose pleco, albino cories. Sword, vals, hygros, ludwigias, java moss and fern, anubias
2g Mac-quarium. Clown gravel, fluorescent plastic plants, and 2 guppies.