Refugiums, pH, o2

[Back where it all began]

Hey,
So we run refugium lights at night, or off cycle, to minimize pH and o2 fluctuations. I have no problems with this as I do it too.
My question is, what happens in an ocean reef at night? Does the pH and o2 fluctuate as the sun sets, or is the shear volume of water offsetting this. I’ve been thinking about ocean reef water flow and I wonder if the water around the reef stays near or if it is constantly being replenished and replaced with sea water from far outside the reef.
In our small tanks, the dynamics are far different of course, but I still ponder the need to run refugium lights off cycle with the main tank lights.
Any thoughts?

 

[Cory]

O2 can drop in deeper parts. Not sure about co2 but logic says it will raise lowering ph slightly because less photosynthesis happens.

 

[Back where it all began]

Thanks. Anyone else? Are we to assume that the ocean/reefs are always nearly constant?