Ever since closing all the windows and running the A/C, I've been having a low pH on my tank. It falls to 7.7 at night, 7.9 during the day. Alk is OK at around 10 dKH so am not that concerned, but I would like to not run things that low. What have folks done to combat this problem? I have just decided to run the air suction on my skimmer outside to fresh air to see if that helps. I also see a few folks run the skimmer air through CO2 removal media like calcium hydroxide.