PH swings from 8.3 to 8.55

[authentic]

Looking for a reason this is happening during the day. Alk 8.2 steady and all other parameters in check .what effect would this have on my sps ?

 

[Reeferdood]

I assume these readings are from a probe?
How old is it and when was it calibrated last?

 

[Randy Holmes-Farley]

It may not be accurate, but if it is, it is perfectly fine. pH swings from photosynthesis during the day consuming CO2 and respiration all the time producing it.

May tank ran in that range for years.

 

[G8trBait16]

I have been running a DIY CO2 scrubber and my ranges are about them same. During the day it hits about 8.55 and 8.27 at night. If the sliding glass doors are open at night bc it is nice out, it won't go any lower than 8.32.