PH and water density/flow?

[banditpowdercoat]

I am still trying to figure out why my Coast to Coast Herbie changes in drain flow. Sometimes the level is high, then later, it drops to making a gurgling sound.

I was thinking it was temp? Hotter water in evening, less dense and would not flow as much in the drain. But, temp has been pretty much constant last 2 days and level stayed just at the drain level, making sucking noise. Other thing that I notice changes between day/night, my PH swings .about .3 between night and day.

Could the PH affect how water flows in a pipe?