PH has me baffeled

[Devildoc]

OK here is a really short version I've been dosing 180 ml every 12 hrs or longer to bring up my alk I am dosing with baking soda mixed with ro/di my pH is usually around 8.2 and hits about 8.3 by the end of the day last couple days at the end of the day it is 8.5 and comes down once the lights go out. Also just started to notice hair algae which I didn't have before but I think my tank cycled which I was trying to avoid when moving it from my 125 to this 220.. but I thought baking soda would lower the pH and soda ash would raise it?

 

[Reefing Madness]

Baking soda will have a small pH lowering effect in most situations unless it's baked. You are correct, Ash will raise is somewhat.
Basically the article explains while there will be an immediate pH change when adding an alkalinity supplement, the changes are really only temporary. The degree of aeration of your tank and the amount of carbon dioxide the air of the room that houses your tank will alter the time it takes for your tank to reach equilibrium and therefore effect the time it takes for or the pH to stabilize at its final stabilized pH. Ultimately with a saturated solution the pH end point will be at about 8.3 to 8.4
Chemistry And The Aquarium: The Relationship Between Alkalinity And pH ? Advanced Aquarist | Aquarist Magazine and Blog