By using this calculator:
http://reef.diesyst.com/chemcalc/chemcalc.html
For a 30 gal tank dissolve 2 tsp of baking soda in water (I use RO/DI) to boost your alkalinity from 2 meq/lt to 3meq/lt
Dont add the solution all at once to your aquarium, add a little at a time perhaps over a day and keep an eye on your pH if you can.