What besides CO2 suppresses PH? I'm at my wits end. I am dosing Kalk during DT lights off. Ran the skimmer line out. Placed 2 air stones with a pump outside. Running a larger fuge when my DT lights are off. Lowered my surface agitation. All this helped but very little. Had the windows closed for the past 2 days. This trashed my PH. The first day there was no increase during my DT lights on. A PH increase of .2 during my DT lights off presumably due to the Kalk and the fuge. It then dropped .2 when the DT lights came back on. Today I placed the first air stone in and got it to hold. I put another in and got it to increase by .1. I have gave up and open the door to let some air in. What can be decreasing my PH besides CO2 ? What else can I do? I have to have the the windows and doors up just to get it above 7.8 it wants to stay in the low 7.6s with out the door open. That's not going to be an option for too much longer and Im concerned with what to do to mitigate the cold months. My house is about 2700 sq/ft and there are 3 adults 2 children. I feel that if my CO2 was so high that its the sole culprit of this low PH there would be health issues associated with that so that has me concerned. I am not able to get a CO2 monitor at this time. While it is clear that CO2 is definitely a contributing factor I feel like there is something else also responsible for these numbers. Even with my windows open, dosing 2500ml of kalk, and running the fuge the best I can get is 8.2 and that takes several days to get to it. Any help would be great appreciated.