Definately up the co2. I hardly ever measure ph but when I did, I was close to a 1.2-1.4 point drop. Your dc should be a solid green at startup than your 5hr pic. It's hard to tell but I can still see a blue tinge in that pic. My dc is usually a light green at startup and almost yellow at the end. I use a 5dkh(sold as 4 but was 5 when I tested) so I actually have more co2 than the same colors using 4dkh. Green using 5dkh is around 45ppm and yellow is 60ppm+ so I have quite a bit of co2 going into my tank. I do have lots of surface agitation though to compensate.