You have plenty of media left in the scrubber looking at the color change going on. The ph can fluctuate on a daily if not hourly basis due to the increase or decrease amount of CO2 entering the tank water. Spending more time in your basement more than normal could be the cause. My tank is in the lower level of my house along with my wife's craft room, and when she spends a large amount of time down there the upper limit of my desired ph either does not quite make it or takes longer to reach it. Same goes when my dogs decide to spend time in the lower level.My ph is a bit lower than usual today. Im at 8.22 from 8.28 is that means my media is getting depleted. The color changing is only at the bottom part. Maybe because i spent a lot of time in tje basement today, doing water testing i dont know.