akundochi
How can I increase the PH without having to dose PH buffer daily?
Your issue is the issue of many, it is slightly high CO2. DO NOT chase your pH with a buffer that is a NO-NO. All you will do is temporarily increase the pH, the Alk will go up, the pH will fall again you will add more buffer to do the same and before long the Alk will be through the roof. Leave what you have alone, it is fine. You try to fix that and you will have a mess.
8.09(night) to 8.13(day)
Many people in this hobby would kill for those Numbers
With your numbers of dKH @ 9.3 your pH should be ~8.35. One has to remember that when one bumps up their Alk they also bump up their CO2. For the sake of argument, if your pH was that 8.13 and your Alk was 6 dKH, the Alk of NSW, your pH should be 8.18. So, where is the extra CO2 coming from
1. Slightly high room air CO2, which drives CO2 into the water. Fix, run outside air to the skimmer or much better, a CO2 scrubber or a sump as a
Refugium
2. Tank not so clean with being slight over stocked or to much feeding. The obvious, slow done the feeding and siphon off crap collected on the bottom.
If you tank was mine I would leave it alone and STOP adding buffer for pH. If your Saintly is 33-36 ppt and your temp 75 - 80F, at an extreme, there will only be a 0.,01 pH difference. 99% of all low pH issue are from CO2 and 75 % of the time it is from room air CO2.