How much does limewater increase ph?

[kevensquint]

Hello, I have high CO2 in my home, with the skimmer intake outside my night Ph went up from 7.6 to 7.8. I looked at an online reef calculator and it seems I can dose a fairly large amount of limewater during the night to maybe increase that a bit more. According to this calculator by adding 500ml limewater to 160 gallons of tankwater, my calcium would barely increase and my Alk would only increase by 0.2 DKH. But what effect would that 500ml limewater have on my Ph.?
Thanks

 

[Randy Holmes-Farley Verified Community Expert]

One cannot say how much it elevates pH when added slowly because it depends on how much aeration is happening at the same tie, but when adding enough all at once to boost the alkalinity by 1.4 dKH, the pH would instantly rise by about 0.6 pH units. It then drops over subsequent hours.

Most folks do see a useful rise of something like 0.1 pH unit or more when dosing slowly. My pH ran 8.35 to 8.55 daily swing when using it.