If you ran the tube out side your equipment room to another room you are still drawing in air from the inside of your home, and still drawing in high CO2. Your can run the tube outside of the house or try a co2 scrubber. Have you tried opening the windows in your house to let in fresh air and see if this has any affect on the pH? I have the same problem. When I can open my windows my pH can increase significantly. I use the following products with good results.
http://www.bulkreefsupply.com/brs-universal-co2-scrubber.html
http://www.bulkreefsupply.com/brs-color-changing-medical-grade-co2-absorbent.html
I was struggling with my pH as well. This was a new tank that is located in the master bedroom, and suffers from a build up of CO2 at night. I have big double doors out to the patio that I try to keep open as much as possible during the day (weather permitting), but my pH was peaking just above 8.0; and would drop as low as 7.6 at night if the room stayed closed up too long. I wound up installing the BRS scrubber, and it worked quite well getting my peak pH up to about 8.2 when combined with having the doors opened all day. However, the media depleted pretty rapidly. It was degraded enough to warrant replacing after a week, and completely spent after two weeks.
Then I started checking my alkalinity, which I had not been paying attention to since the tank did not yet have any corals. Turns out that my alkalinity was at 5.4 dKH, which was unexpected since there was nothing in the tank yet that should be consuming it. I believe the salt mix I used (Aqua Forrest Reef Salt) must have started off low to begin with. I gradually brought my alkalinity up to just over 9 dKH dosing sodium bicarbonate. The sodium bicarbonate temporarily depressed the pH, but it bounced back quickly after each addition, and has been much more stable overall since. Even with the scrubber media fully depleted, I am now able to get my pH up to as high as 8.16 with fresh air alone, and keep it from going below 7.9 during the night.
I think it goes to show how these things interact, and you can't just worry about one in isolation from the others. In my case, the low pH appears to have been due to the combination of CO2 build up AND low alkalinity; not just one or the other. My calcium was also reading above 500 before I adjusted the alkalinity. Now it's down to 432 ppm. The lesson I am taking away is, if one parameter is off, go ahead and check everything else too even if you think you already know the reason it was off.
I'm now working on figuring out a way to add a vent to exchange fresh air into the sump without the need to keep the doors to my room open all day. Summer is coming, and that isn't going to be practical when it gets really hot. I will go back to using the CO2 scrubber as well once I begin adding corals. I'm thinking of rigging it up to my Apex controller though so that it can be turned on or bypassed according to the pH probe readings. Hopefully that will make the media last longer. At the current rate, one refill per week works out to about $6.43 per refill. Not too horrible, but it also adds an extra weekly maintenance item to worry about, and I would rather stretch it out a bit further if possible. For right now, I'm not bothering with it because the fish are fine with the pH where it is.
