PH and ORP swings

[Reefcube]

For the last couple night my ph has been falling to 7.63 and orp goes up then when the lights come on ph goes up and orp back down. I have been dosing with esv 2 part trying to raise ph up.

 

[Reeferdood]

7.63 is on the low side of the preferred range. Either the probe needs recalibration or you actually have excess C02 in the home. Use of a c02 scrubber before the skimmer inlet or fresh air from the outside might help. Kalkwasser is also another option to raise pH that is low.