Soda ash is baked (400 degrees for an hour) baking soda, the heat gasses off the co2 therefore has less impact on ph
I space mine out through out the day. For example right now with hardly any corals in my tank I think I’m at 50ml a day at 6, 12, 18 and24:00. Before when my tank was packed it was like 250 ml a day either every hour or every other hour I can’t remember.