Ahh, been reading here a while and this is the 1st time I saw an explanation for Borax vs PH up - Borax does not increase ALK but you need more of it. I think I even asked the question once because the bleach calc says "soda ash, not Borax" to raise PH.
So Soda Ash or PH up is OK if you can allow for PH increase and Borax to raise PH if you don;t want an additional increase in ALK.