manually dosing Alk

[e46er]

so for those who manually dose alk.

i bought a 1.2 Kg thing of seachem reef builder and its now running low

it always raised the alk what it said it would using this calculator
http://jdieck1.home.comcast.net/~jdieck1/chemcalc.html
but its $20 bux at JL

do you guys buy the expensive name brand products or use baking soda?
or baked baking soda? and how long do you bake it?