baking soda in top off ?
 

75 gallon tank with sump approx 100 gal total currently dosing manually everyday would adding this to top off be a bad idea ? I know evap changes everyday based on weather etc oh is always higher 8.7 we keep Windows open all the time any help would be appreciated thanks

I used to do that , but got a keep an eye on it. You don't want the Alk to go up & down too much . A better way is to get a Doser . Then you don't have the variance of evaporation.

I assume it worked for you I'm too cheap to buy a doser atm

Oh Ya . Poor mans Doser !

Calcium hydroxide (Kalk) is more common as it can maintain both calcium and alkalinity. Many people have or still use this approach so certainly nothing wrong with it. For an extra boost you can use a Kalk reactor inline with a top off, it can also allow some adjustment based on how often its stirred.